Improve screen navigation: database > scheme > table

[avelino]

Is your feature request related to a problem? Please describe.
The navigation is table-only, with the possibility to enter a table and edit

I have to declare via an environment variable the database and schema — this is dynamic on prestd (server)

Describe the solution you'd like

1. on the first page: list the databases
2. second page: list schemas of the selected database
3. third page: list tables for the selected database and schema
4. fourth page: list data for the selected table (from the database and schema)