Handle EME key status errors such as "internal-error" and "output-restricted" before appending media

[robwalch]

This PR will...

• Handle EME key status errors such as "internal-error" before appending media
• Ban keys with status "internal-error" so that additional license requests are not made for them when found in other playlists
• Fallback to variants and renditions that have not been loaded or do not contain the key
• Multiple key status changes in a single session are handled based on the session playlist key ID
• Sessions where the playlist key ID changes to status "internal-error" are closed
• Remove levels with unresolved key status errors ("internal-error" or "output-restricted" w/o defined HDCP-LEVEL attributes)

Why is this Pull Request needed?

@yajin2021 reported that other variants should be selected when a key error occurs:

• Automatically try other bitrate videos when key error occus #7401
• The playback ends when the "keySystemStatusInternalError" occurs #7413

Preventing appends of media with bad keys prevents the CDM from locking up playback. I was not able to append the media optimistically, and then remove it from the buffer on key error before a switch. Either hls.js queued too much media (appending more after the first key error) or any appends that cannot be decrypted interfere with playback.

Are there any points in the code the reviewer needs to double check?

Created #7474 for #7414 (comment) to be addressed in a future release.

• Multi-key handling #7474

Resolves issues:

• The playback ends when the "keySystemStatusInternalError" occurs #7413
• HDCP error when playing manifests with both HD and SD levels #7469

Checklist

• changes have been done against master branch, and PR does not conflict
• new unit / functional tests have been added (whenever applicable)
• API or design changes are documented in API.md

[robwalch]

Commented on flaws in MediaKeySessionContext that limit handling of key sessions to a single key ID. Grouping of sessions by KEY URI and handling multiple keys (level key objects and key statuses) will be addressed in a future release.

hls.js/src/controller/eme-controller.ts

Lines 55 to 60 in 7a089f0

	export interface MediaKeySessionContext {
	keySystem: KeySystems;
	mediaKeys: MediaKeys;
	decryptdata: LevelKey; // FIXME: LevelKey has a URI which should be bound to the session, but is dependent one KeyId specifically. Session context should be allowed to adopt multiple level keys.
	mediaKeysSession: MediaKeySession;
	keyStatus: MediaKeyStatus; // FIXME: MediaKeySession can manage multiple keys with each with its own status