Fix [clip_media] reviewable.

[robin-ynput]

Changelog Description

While working on retimes, I realized I've over-engineered the logic to handle [clip_media] reviewable.
When selected the reviewable should be otio_clip original media source range + handles.

This change simplify the approach to make it leverage collect_otio_review, extract_otio_review and extract_review.

Changes:

• Rework [clip_media] logic to make it go through collect_otio_review
• Ensure single frame reviewables are properly handled by extract_review plugins

Testing notes:

1. From Flame or Hiero publish shot clip with the [clip_media] reviewable enabled
2. Ensure reviewable is properly produce from clip source range (no retime applied) + handles

[jakubjezek001]

works like a charm!