FF Tables: Improve empty state for "Select a table" (add a small graphic or better guidance)

[cstns]

This is our empty state message for the FF Tables page.

The only way a user can access this state is when he doesn't have any tables at all.

This is the view for when the feature is not enabled for the team:

If the user has existing tables, they the first one is pre-selected when accessing the page and the user doesn't have the option/possibility to un-select a table