frontend: Add MediaControls to source properties

[Warchamp7]

Description

Depends on #8041 which I recently rebased.

Adds the MediaControls component to the source properties window for sources with the OBS_SOURCE_CONTROLLABLE_MEDIA flag.

Motivation and Context

More ways to control media playback besides the context bar.

How Has This Been Tested?

Tested with Media Sources using a local file and an Image Slideshow source.

Types of changes

• New feature (non-breaking change which adds functionality)
• Tweak (non-breaking change to improve existing functionality)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.