Disable metadata parsing

[OxygenCobalt]

[REQUIRED] Use case description

My app now uses it's own metadata extractor, and has no dependence on ExoPlayer's metadata extractor, only it's basic container parsing and codec handling. As a result, this default metadata code remains and both bloats app size and uses additional memory during playback.

Proposed solution

A way to configure extractors to not parse (optional) metadata in such a way that proguard can strip it out from the app.

Alternatives considered

Patching the support out myself, but this seems brittle.