FAL-2482 [LX-2242] inline transcripts for audio blocks

[samuelallan72]

FAL-2482 | LX-2242

These changes are to support the transition from srt subtitles to inline html transcripts for audio blocks.

Test instructions:

• test as part of opencraft/client/LabXchange/labxchange-dev!1532
• read the code and verify the logic is correct and desirable