- Removed the Xamarin.Essentials package from osu.Game and added it to osu.iOS and osu.Android only.
- iOS and Android implementations use Xamarin.Essentials.Battery, while the Desktop implementation
only returns 100% battery for now.
- Added a BatteryCutoff property to PowerStatus so it can be different for each platform (default 20%, 25% on iOS)
This also removed a previous attempt at the same thing, which happened
to not be applying due to the reference to the applied bindable not
being held. Whoops.