Feature: Buffering configuration for android

[andreasgangso]

This is a good first issue.

1. Create a class in playback_platform_pigeon.dart (see pigeons readme), something similar to [betterplayers BufferingConfiguration], something similar to betterplayers BufferingConfiguration
2. Pass it as argument to newPlayer() because you probably can't change it for an existing exoplayer.
3. ExoPlayerController just needs to setLoadControl() with the values. Something like this: https://github.com/jhomlala/betterplayer/blob/f6a77cf6fbb515f01aa9fb459b2ee739de3e724c/android/src/main/kotlin/com/jhomlala/better_player/BetterPlayer.kt#L101