Populate database entry for connection dialog with list of databases on the specified server

[Benjin]

Currently, the database input is a textbox for parameter-mode in the connection dialog. Ideally, the connection dialog should silently attempt to connect to the database once server+auth info is populated, and provide a combobox with valid databases options populated to the user.

Note: the Azure browse experience already uses a combobox for the database entry, but that's because that info was pulled from the Azure plane, not from the database.