Move transcript_utils to video-config

[farhan]

Movexmodule/video_block/transcripts_utils.py to openedx/core/djangoapps/video_config

As part of the ongoing effort to deprecate and eventually remove xmodule, we’ve started gradually migrating the necessary code files from xmodule to more appropriate locations within the codebase.

[kdmccormick]

Closed by openedx/openedx-platform#37600