Hybrid version for Xamarin and MAUI

## 🏗 Enhancement Proposal

Get a Hybrid version of MediaManager to use with both Xamarin.Android / Xamarin.iOS projects and MAUI projects

### Pitch

Existing Xamarin apps can use the latest Android 12 compatibility fixes in ExoPlayerXamarin, and work their way towards the upgrade to of their apps MAUI.

Possible approach:
1. Publish separate Nuget packages of ExoPlayerXamarin for Maui and for Xamarin.Android (based on [this](https://github.com/Baseflow/ExoPlayerXamarin/pull/145) discussion.)
2. Add references to the packages based on the target framework (`.net-xxx` / `mono-android-xxx`)
3. Fix the build errors, possibly using some compile time constants

Alternative approach: Publish separate packages for MediaManagerMAUI and XamarinMediaManager, based on possibly separate branches

### Platforms affected (mark all that apply)
- [X] :iphone: iOS
- [X] :robot: Android
- [ ] :checkered_flag: WPF
- [ ] :earth_americas: UWP
- [ ] :apple: MacOS
- [ ] :tv: tvOS
- [ ] :monkey: Xamarin.Forms

Start by reviewing the proposed ExoPlayerXamarin PR 145 discussion and the repository's package references for .net-xxx and mono-android-xxx target frameworks. The issue names no files, tests, or entry points; done would require a decided packaging approach, successful Xamarin and MAUI builds, and working iOS and Android packages.

Written by the indexing model from the issue text.