olly 0ad508b14f Rename TracksInfo and TrackGroupInfo
1. TracksInfo is renamed to Tracks
2. TracksInfo.TrackGroupInfo is renamed to Tracks.Group

PiperOrigin-RevId: 441232373
2022-04-26 14:59:00 +01:00
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2022-04-26 14:59:00 +01:00