Support SCORE for prioritization of specific variants within a playlist

[robwalch]

Is your feature request related to a problem? Please describe.

Currently, HLS.js only uses SCORE for arbitration when no factors other than playlist order remain in selection. This is incorrect.

Describe the solution you'd like

Always pick a variant from those with the highest SCORE, except those that are unplayable or would degrade playback (stall).

The best way to score variants is in tiers. Give multiple bitrate variants in an adaptation set (with the same codecs) the same score. The "better" or more efficient sets should be assigned the highest score. This will force the client to select the preferred adaptation set according to available resources. Unsupported variants or variants that cannot be played without stalling should not be chosen, regardless of SCORE.

Additional context

No response