Add empty state messages in breadcrumb selectors

[pavish]

Description

• Before Improve nav header behavior #4072, the navigation header was inconsistent among pages as described in Make navigation header behave more consistently #3287.
• Previously the navigation then did not include item selectors of children. eg., if you are on the schemas page, there is no selector after it on the header to select tables.
• Now, we have an item selector on the header for child entities.
• There is currently no empty state when child entities are not present.
• Open the application for the first time with no databases and click on the dropdown selector next to the logo:
  • 
• Open a schema with no tables and click the dropdown
  • 

Expected behavior

• Database selector:
  • When there are no databases, we should display a "No Databases configured" text in the dropdown.
  • We should display a peristent link to "Connect a database".
• Schema selector:
  • When there are no schemas, we should display a "No Schemas configured" text in the dropdown. (The public schema can be deleted)
• Table selector:
  • When there are no tables, we should display a "No Tables configured" text in the dropdown.

[ShailRT]

can i work on this issue?

[ShailRT]

is something like this acceptable?

[sharath-1517]

is something like this acceptable?

Hey @ShailRT, you can make all those needed changes same like this in those three sections that Pavish has mentioned and then make a PR for it. Since it's Christmas and the New Years coming up they'll not be able to get back to you as fast as they always do. So make sure you make those changes, make a PR and wait and relax :) Rest assured! Thanks...

[ShailRT]

@sharath-1517 okay sure