This moves `SelectionOverride` from `DefaultTrackSelector`
to `TrackSelectionParameters`.
It is then use to allow track selection override per
track selection array.
Note that contrary to
`DefaultTrackSelector.Parameters.selectionOverride`, the renderer
concept is not exposed.
This cl is a part of the bigger track selection change,
splitted for ease of review.
Find all cls with the tag:
#player-track-selection
PiperOrigin-RevId: 399933612
