Rework OnboardApp to adjust to new architecture

[TimoPtr]

Summary

This PR cleans up the OnboardApp class and keep it only for the wear onboarding since it is not needed for the rest while removing all the useless parameters.

Checklist

• New or updated tests have been added to cover the changes following the testing guidelines.
• The code follows the project's code style and best_practices.
• The changes have been thoroughly tested, and edge cases have been considered.
• Changes are backward compatible whenever feasible. Any breaking changes are documented in the changelog for users and/or in the code for developers depending on the relevance.

Any other notes

I tested the onboarding on TV, mobile and wear.

[jpelgrom]

I don't think this is for Wear, and it's also a behavior change I don't fully understand the reasoning behind. Can you elaborate / pull it out into another PR?

[TimoPtr]

It was called in the results of the onboarding after adding a server. If you look at the old code activity result in settings you would see that. I moved it here so it replicates the same behavior as before.

[jpelgrom]

For app usage it may replicate the same usage, but now it also tries to active the Wear server on the phone that started onboarding it, no?

[TimoPtr]

It's probably not clear enough and would deserve a comment in the nameyourweardevice package that actually it uses the screen but not the view model actually.

So no it doesn't activate the server on the wear onboarding.

[jpelgrom]

Yes please add a comment as that seems like something you may easily miss like I did