SDK / exoplayer

- Deprecate old Format.createXXX methods
- Deprecate most Format.copyXXX methods
- Stop using deprecated Format.copyXXX methods in the library

Note: Replacing library usages of Format.createXXX method
will be done in follow up CLs. These changes aren't purely
mechanical because we need to decide which out of peakBitrate
and averageBitrate to set in each case where currently a
single bitrate is provided.

Issue: #2863
PiperOrigin-RevId: 296450935