[Proposal] [v4] Errors: Replace trackInfo prop by tracksInfo to group similar errors

[peaBerberian]

After doing many tests, it seems that the strategy of sending a MANIFEST_INCOMPATIBLE_CODECS_ERROR warning each time we spot an audio or video AdaptationSet with no supported codec in the MPD is not optimal for very large MPD (or equivalent in smooth streaming / local Manifests / MetaPlaylists).

Specifically, MPD with a very large amount of unsupported AdaptationSet (multi-Period MPDs, MPDs with a large choice of AdaptationSet with multiple codecs, dynamic range, audio channels, or all of this together), might produce A LOT of warnings - even more for contents where the Manifest has to be updated.

In turn, those warnings produce a lot of uninteresting warning logs, and might have in some extreme cases a non-null impact on memory as parsing issues were until known stored as a property of the Manifest instance (still less than a MB in the current worst observed cases - so not THAT problematic either, but still).

This PR propose for the v4 the following changes:

• All MANIFEST_INCOMPATIBLE_CODECS_ERROR warnings seen while parsing a Manifest are regrouped into one - even when talking about media of different types (i.e. "audio" and "video")

• The trackInfo stored on some MediaErrors is now renamed into tracksInfo (with an s) and is now an Array of tracks - to allow warnings for multiple tracks at once. This is sadly a breaking change - it is relatively minor as trackInfo was optional and a very recent addition - but still, we only authorize ourselves this on the v4 because it is still in beta.

• A Manifest instance does not "store" the warnings as a property as this is not needed by anything and this is not in the API. This was mainly done because it was the simplest way to implement it - but grouping warnings together now need a more advanced solution anyway.