Fix rotation metadata loading incorrectly with FFMPEG 6

[chxmberland]

Linked issues #496

Summarize your change.

Added an additional check to another metadata field when loading movie clips to ensure that rotation metadata is captured correctly.

Describe the reason for the change.

In FFmpeg 6.0, rotation metadata can be loaded incorrectly without this check.

Describe what you have tested and on which operating system.

macOS Sonoma 14.5

Add a list of changes, and note any that might need special attention during the review.

• Added an additional check to the side_data field when movies are loaded in to RV
• Covered additional cases of negative rotation metadata, as this was not covered already

If possible, provide screenshots.