Fix live duration override by interstitials

[robwalch]

This PR will...

Ignore non-finite MediaSource duration overrides.

Do not set duration to Infinity in getDurationAndRange as this can throw when SourceBuffers are updating.

Why is this Pull Request needed?

Prevents Interstitial asset players from resetting duration on transferred MediaSource when the schedule duration is Infinity for a live primary asset and liveDurationInfinity is false.

Duration is already set in updateMediaSource between blocking operations and should never be set in getDurationAndRange.

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

Only applies to live playback with Interstitials with default liveDurationInfinity of false (set to true to workaround this issue).

Resolves issues:

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