1) Added partition module in webpack config.

2) Fixed missing logic of partition from primary_key.js and unique_constraint.js as this two files are newly created for webpack.
3) Changed the node name from 'check_constraint' to 'check_constraints'. Also changed the same in test case url.

web/webpack.config.js

@@ -195,7 +195,8 @@ module.exports = {
         ',pgadmin.node.catalog_object_column' +
         ',pgadmin.node.view' +
         ',pgadmin.node.mview' +
-        ',pgadmin.node.table',
+        ',pgadmin.node.table' +
+        ',pgadmin.node.partition',
       },
     }, {
       test: require.resolve('./node_modules/acitree/js/jquery.aciTree.min'),