Redesign Generator App - UI Steps

Change UI of Generator App with UI steps (location):
1) List of connections (recent list + all definitions list) and Connect action
2) Design SQL and execute SQL
3) Review fetched data and generate proxy&fake
4) Review generated code and set proxy&fake options

Important notes:
- Each location (step) will be designed as a separate form
- Location will be embedded into main view
- Back button will allow to take step back

Start with the Generator App's main view and map the four requested locations: connections, SQL design and execution, fetched-data review, and generated-code review. Treat each location as a separate form embedded in the main view, with Back navigation between steps; done means all four steps and backward navigation are represented in the UI.

Written by the indexing model from the issue text.