Added and fixed gettext usage for better translation coverage. Fixes #5284

1) Fixed usage gettext('') instead of _('') in javascript files.
  2) Fixed usage gettext('') instead of `${gettext('')}` in javascript files,
     because "pybabel extract" not support extracting from this syntax.

web/pgadmin/browser/server_groups/servers/databases/casts/__init__.py

@@ -50,7 +50,7 @@ class CastModule(CollectionNodeModule):
     """
 
     NODE_TYPE = 'cast'
-    COLLECTION_LABEL = 'Casts'
+    COLLECTION_LABEL = gettext('Casts')
 
     def __init__(self, *args, **kwargs):
         super(CastModule, self).__init__(*args, **kwargs)

web/pgadmin/browser/server_groups/servers/databases/event_triggers/static/js/event_trigger.js

@@ -111,10 +111,10 @@ define('pgadmin.node.event_trigger', [
           id: 'enabled', label: gettext('Trigger enabled?'),
           group: gettext('Definition'), mode: ['properties', 'edit','create'],
           options: [
-            {label: 'Enable', value: 'O'},
-            {label: 'Disable', value: 'D'},
-            {label: 'Replica', value: 'R'},
-            {label: 'Always', value: 'A'},
+            {label: gettext('Enable'), value: 'O'},
+            {label: gettext('Disable'), value: 'D'},
+            {label: gettext('Replica'), value: 'R'},
+            {label: gettext('Always'), value: 'A'},
           ],
           control: 'select2', select2: { allowClear: false, width: '100%' },
         },{
@@ -125,9 +125,9 @@ define('pgadmin.node.event_trigger', [
           id: 'eventname', label: gettext('Event'),
           group: gettext('Definition'), cell: 'string',
           options: [
-            {label: 'DDL COMMAND START', value: 'DDL_COMMAND_START'},
-            {label: 'DDL COMMAND END', value: 'DDL_COMMAND_END'},
-            {label: 'SQL DROP', value: 'SQL_DROP'},
+            {label: gettext('DDL COMMAND START'), value: 'DDL_COMMAND_START'},
+            {label: gettext('DDL COMMAND END'), value: 'DDL_COMMAND_END'},
+            {label: gettext('SQL DROP'), value: 'SQL_DROP'},
           ],
           control: 'select2', select2: { allowClear: false, width: '100%' },
         },{

web/pgadmin/browser/server_groups/servers/databases/external_tables/properties.py

@@ -52,8 +52,8 @@ class Properties:
         execute_on_text = self.translate_execute_on_text(execute_on)
         response = dict(
             name=table_information_result['name'],
-            type=gettext('readable' if not table_information_result[
-                'writable'] else 'writable'),
+            type=gettext('readable') if not table_information_result[
+                'writable'] else gettext('writable'),
             format_type=table_information_result['pg_encoding_to_char'],
             format_options=table_information_result['fmtopts'],
             external_options=table_information_result['options'],
@@ -65,14 +65,14 @@ class Properties:
     @staticmethod
     def translate_execute_on_text(execute_on):
         if execute_on['type'] == 'host':
-            return 'host %s' % execute_on['value']
+            return gettext('host %s') % execute_on['value']
         elif execute_on['type'] == 'per_host':
-            return 'per host'
+            return gettext('per host')
         elif execute_on['type'] == 'master_only':
-            return 'master segment'
+            return gettext('master segment')
         elif execute_on['type'] == 'all_segments':
-            return 'all segments'
+            return gettext('all segments')
         elif execute_on['type'] == 'segment':
-            return '%s segment' % execute_on['value']
+            return gettext('%s segment') % execute_on['value']
         elif execute_on['type'] == 'segments':
-            return '%d segments' % execute_on['value']
+            return gettext('%d segments') % execute_on['value']

web/pgadmin/browser/server_groups/servers/databases/schemas/tables/constraints/exclusion_constraint/static/js/exclusion_constraint.js

@@ -450,7 +450,7 @@ define('pgadmin.node.exclusion_constraint', [
           titleTmpl = _.template([
             '<div class="subnode-header">',
             '  <label class="control-label pg-el-sm-10"><%-label%></label>',
-            '  <button class="btn btn-sm-sq btn-secondary add fa fa-plus" <%=canAdd ? "" : "disabled=\'disabled\'"%> title="' + _('Add new row') + '"></button>',
+            '  <button class="btn btn-sm-sq btn-secondary add fa fa-plus" <%=canAdd ? "" : "disabled=\'disabled\'"%> title="' + gettext('Add new row') + '"></button>',
             '</div>'].join('\n')),
           $gridBody =
           $('<div class=\'pgadmin-control-group backgrid form-group col-12 object subnode\'></div>').append(

web/pgadmin/browser/server_groups/servers/databases/schemas/tables/constraints/foreign_key/static/js/foreign_key.js

@@ -378,7 +378,7 @@ define('pgadmin.node.foreign_key', [
           titleTmpl = _.template([
             '<div class="subnode-header">',
             '  <label class="control-label pg-el-sm-10"><%-label%></label>',
-            '  <button class="btn btn-sm-sq btn-secondary add fa fa-plus" <%=canAdd ? "" : "disabled=\'disabled\'"%> title="' + _('Add new row') + '"></button>',
+            '  <button class="btn btn-sm-sq btn-secondary add fa fa-plus" <%=canAdd ? "" : "disabled=\'disabled\'"%> title="' + gettext('Add new row') + '"></button>',
             '</div>'].join('\n')),
           $gridBody =
           $('<div class=\'pgadmin-control-group backgrid form-group col-12 object subnode\'></div>').append(

web/pgadmin/browser/server_groups/servers/databases/schemas/tables/partitions/static/js/partition.js

@@ -71,12 +71,12 @@ function(
           // To enable/disable all triggers for the table
           name: 'enable_all_triggers', node: 'partition', module: this,
           applies: ['object', 'context'], callback: 'enable_triggers_on_table',
-          category: 'Trigger(s)', priority: 4, label: gettext('Enable All'),
+          category: gettext('Trigger(s)'), priority: 4, label: gettext('Enable All'),
           icon: 'fa fa-check', enable : 'canCreate_with_trigger_enable',
         },{
           name: 'disable_all_triggers', node: 'partition', module: this,
           applies: ['object', 'context'], callback: 'disable_triggers_on_table',
-          category: 'Trigger(s)', priority: 4, label: gettext('Disable All'),
+          category: gettext('Trigger(s)'), priority: 4, label: gettext('Disable All'),
           icon: 'fa fa-times', enable : 'canCreate_with_trigger_disable',
         },{
           name: 'reset_table_stats', node: 'partition', module: this,

web/pgadmin/browser/server_groups/servers/databases/schemas/tables/static/js/table.js

@@ -82,23 +82,23 @@ define('pgadmin.node.table', [
         },{
           name: 'truncate_table', node: 'table', module: this,
           applies: ['object', 'context'], callback: 'truncate_table',
-          category: 'Truncate', priority: 3, label: gettext('Truncate'),
+          category: gettext('Truncate'), priority: 3, label: gettext('Truncate'),
           icon: 'fa fa-eraser', enable : 'canCreate',
         },{
           name: 'truncate_table_cascade', node: 'table', module: this,
           applies: ['object', 'context'], callback: 'truncate_table_cascade',
-          category: 'Truncate', priority: 3, label: gettext('Truncate Cascade'),
+          category: gettext('Truncate'), priority: 3, label: gettext('Truncate Cascade'),
           icon: 'fa fa-eraser', enable : 'canCreate',
         },{
           // To enable/disable all triggers for the table
           name: 'enable_all_triggers', node: 'table', module: this,
           applies: ['object', 'context'], callback: 'enable_triggers_on_table',
-          category: 'Trigger(s)', priority: 4, label: gettext('Enable All'),
+          category: gettext('Trigger(s)'), priority: 4, label: gettext('Enable All'),
           icon: 'fa fa-check', enable : 'canCreate_with_trigger_enable',
         },{
           name: 'disable_all_triggers', node: 'table', module: this,
           applies: ['object', 'context'], callback: 'disable_triggers_on_table',
-          category: 'Trigger(s)', priority: 4, label: gettext('Disable All'),
+          category: gettext('Trigger(s)'), priority: 4, label: gettext('Disable All'),
           icon: 'fa fa-times', enable : 'canCreate_with_trigger_disable',
         },{
           name: 'reset_table_stats', node: 'table', module: this,