SDK / exoplayer

This makes two fixes:
1. Remove `HlsSampleStreamWrapper.Callback` (package-private) from the
   list of interfaces implemented by `HlsMediaPeriod` (`public`) and
   move the implementation to a private inner class instead. This avoids
   Metalava complaining about a public class that inherits from a
   package-private type.
2. Reduce the visibility of
   `RtpPayloadFormat.isFormatSupported(MediaDescription)` from `public`
   to package-private. The `MediaDescription` type is already
   package-private, so this method was already unusable outside the
   package.

#minor-release

PiperOrigin-RevId: 487472781
(cherry picked from commit 9041d7b9)