Back button navigation improvements

## The Problem
In previous versions of the app, before the in-app mapping feature was available, the back button would go back directly. But now, the back button needs to be pressed three times to exit.

- A long back press to return to the remote selection screen.
- A short back press to get to the mapping options screen.
- Then another short back press to exit the app.

## Proposed Solution
### On the main remote selection screen

- Short back press to enter mapping options screen.
- Long back press to exit app.

### On the mapping options screen

- Short back press to return to remote selection (main) screen.
- Long back press to exit app.
#### Not sure if this is a bug, but...
When holding the back button to exit from the app from this screen, the app doesn't exit and makes the screen go blank until back button is released.

### On the remote usage screen
- Short back press to return to remote selection (main) screen.
- Long back press to exit app.

I am on unleashed 65e