Improvement in the look and feel of the whole application

Changed the SCSS/CSS for the below third party libraries to adopt the
new look 'n' feel:
- wcDocker
- Alertify dialogs, and notifications
- AciTree
- Bootstrap Navbar
- Bootstrap Tabs
- Bootstrap Drop-Down menu
- Backgrid
- Select2

Adopated the new the look 'n' feel for the dialogs, wizard, properties,
tab panels, tabs, fieldset, subnode control, spinner control, HTML
table, and other form controls.

- Font is changed to Roboto
- Using SCSS variables to define the look 'n' feel
- Designer background images for the Login, and Forget password pages in
  'web' mode
- Improved the look 'n' feel for the key selection in the preferences
  dialog
- Table classes consistency changes across the application
- File Open and Save dialog list view changes

Author(s): Aditya Toshniwal & Khushboo Vashi

web/pgadmin/tools/maintenance/__init__.py

@@ -130,13 +130,11 @@ class Message(IProcessDesc):
 
         res = '<div>' + html.safe_str(res)
 
-        res += '</div><div>'
-        res += html.safe_str(
-            _("Running Query:")
-        )
-        res += '</b><br><i>'
+        res += '</div><div class="py-1">'
+        res += _("Running Query:")
+        res += '<div class="pg-bg-cmd enable-selection p-1">'
         res += html.safe_str(self.query)
-        res += '</i></div>'
+        res += '</div></div>'
 
         return res