Finish migrating SettingsFragment to ViewModel
This also splits up the UI into sub-screens.
- check that the settings main screen shows icons that are colored like the text in light and dark theme
- enter all new settings screen, check that all settings are enabled as expected (e.g. app lock only enabled when phone has a screen lock)
- change all settings and check that their new value gets persisted across screen rotations as well as leaving settings and coming back
- check that a release build doesn't show developer options and profile pic setting