ci: Return to entrypoint based scanner

[M123-dev]

What

• Nothing special, removing the switch in the dev settings. Now the scanner is again dependent on the entry point which is used.
• I removed the red text above the scanner
• Now we don't use a provider for the scanner type anymore. It won't change during runtime, so I decided to go with a global var

This will likely be a bit restructured in my next PR to allow building completely without ml kit for F-Droid

[monsieurtanuki]

Hi @M123-dev!

I'm really not a big fan of import 'main.dart' whose local variables are being used as global variables.
At least a dedicated class for global variables, so that human beings can read code and understand where scannerType or flavour come from?
Not sure either to which extent global variables are recommended in dart/flutter, but that's another story.

Let's go to the next step!

[M123-dev]

Thanks a lot @monsieurtanuki, yes I agree we should move it to a dedicated file, though probably at least the scanner type one will disappear.