Note that unlike the legacy implementation, custom media items
commands can be used for any media items with Media3 API. This
includes `MediaItem` instances that are received from sources
different to `MediaLibraryService` methods.
Hence when connected against a Media3 session these custom commands
can be used with a `MediaController` as well as with a `MediaBrowser`.
Interoperability with `MediaBrowserServiceCompat` will
be added in a follow up CL.
Issue: androidx/media#1474
#cherrypick
PiperOrigin-RevId: 678782860
686c3fe7f5