The features supported by `TranscodingTransformer` are a
superset of those supported by `Transformer` after merging
the video renderers in
https://github.com/androidx/media/commit/35c891a7bf7c18d2b906fe6a3b0325ca74bcf91f.
This change removes `TranscodingTransformer` and adds its features to
`Transformer`.
PiperOrigin-RevId: 411072392
