unify all scripts in a pwnagotchi companion app

once all scripts (image creation + internet sharing from host) are nice and working, we should unify their functionalities in a single pwnagotchi companion app (maybe in go for easy cross compilation?), some idea for what the app should be doing:

1. Create an image.
2. Share connection from host computer.
3. Setup the usb0 interface automatically on the host if a unit is detected.
4. Update the software of a unit.
5. Backup a unit.
6. Restore a backup.