[pgAdmin][RM2172] Search Objects Functionality

Hi Hackers,

Attached is the patch to implement search objects functionality in pgadmin.

The feature will allow a user to search for any object in a database.

Highlights of the feature:

1) Search any object with user input text with at least 3 characters.

2) Search can be done on a specific object type by selecting from the types dropdown.

3) The search results grid will show object name, object type and the object path on the browser tree. On double clicking the record, it will locate that object on the browser tree. The columns object name and type are sortable.

4) The object nodes which are disabled (hidden) using preferences will not be visible in the types dropdown. However, in the case of all types, the search records will be visible for those types greyed out.
5) You can also access search objects dialog using the button on the browser toolbar.

Python and JS test cases added. Docs updated.

Please review.