Handle onboarding initial errors

[TimoPtr]

Summary

Address the last remaining TODOs from the onboarding. It was about displaying the errors when the app cannot start properly like No network or not supporting some feature like Wear onboarding.

I decided to simplify the state handling of the launcher activity by moving the whole logic into the view model.

Unfortunately I was not able to add screenshots tests for the dialogs it doesn't work.

Checklist

• [x] New or updated tests have been added to cover the changes following the testing guidelines.
• [x] The code follows the project's code style and best_practices.
• [x] The changes have been thoroughly tested, and edge cases have been considered.
• [x] 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.

Screenshots

[TimoPtr]

This Pr can be merged in the base branch once it's approved.

[jpelgrom]

Your dialog is missing dark mode support.

[TimoPtr]

I didn't make a HADialog since I'm not sure if we are going to use them in the end. So for now I've simply made the dialog to use our color (not even the typography)