Fix video dimensions for HLS streams

this fixes the case on any time you have a react view that displays the video, but it's being rendered with controls but not as a full screen (ie. easily reproducible when you have a tabbar for instance - the reactViewController.view frame shouldnt be the whole screen bounds).

This also deprecates the old react-native windows implementation

Also update linting rules to match other community repositories.

Implement audio focus as per android docs:
https://developer.android.com/guide/topics/media-apps/audio-focus
https://medium.com/androiddevelopers/audio-focus-3-cdc09da9c122

AUDIOFOCUS_LOSS should abandon focus and not try resuming audio, this is done with AUDIOFOCUS_LOSS_TRANSIENT

This fixes at least:
- Audio not being paused after focus being taken by some voip applications
- Content resuming and pausing instantly sporadically (some race condition perhaps) when activity was resumed from background.

Fix playerviewcontroller keypath leak of observers

The progress message handler will duplicate recursions of the `onProgressMessage` handler on change of player state from any state to STATE_READY with `playWhenReady` is true (when video is not paused). This clears the messages on STATE_IDLE and STATE_BUFFERING to break the recursion.

fix typo in README

- Bump Exoplayer to 2.10.4
- Remove deprecated usages of Exoplayer methdos
- Add `ReactExoplayerConfig` as extension points to configure the Exoplayer instance