New banking app navigation example

[bizz84]

This is some experimental work that would replace the old example app.

The new app replicates a basic banking application and supports:

• [x] Bottom navigation with tabs
• [x] PageView integration for the content pages
• [x] nested navigation within a tab
• [x] root navigation (above the bottom navigation)
• [x] switch between tabs programmatically (e.g. when a button is pressed)

The current implementation is WIP and still lacks some functionality.