Re-align audio playlist with main when there is no overlap between audio playlist updates

[robwalch]

This PR will...

• Attempt to realign audio with main when alignPlaylists finds no overlap in live playlist updates.
• Wait for audio rendition playlist update when ending discontinuity is not matched in main playlist.
• startCC of LevelDetails will be set to DISCONTINUITY-SEQUENCE when playlists begin with a DISCONTINUITY tag instead of the sequence number of the first fragment (starting sequence +1), allowing alignment on first segment with new discontinuity.
• Prevent audio-stream-controller state changes to "WAITING..." when loading is stopped.

Why is this Pull Request needed?

• Realigns live main and audio playlists after media sequence sync is lost.
• Prioritizes discontinuity sequence alignment over program date time.
• Prevents audio segment fetching of new discontinuity until main discontinuity sequence is avaiable.

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

Audio playlists aligned with main on program date time at start can have negative start times.

Resolves issues:

Resolves #6823

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