obs-ffmpeg: Add quality preset for VA-API

[nowrep]

Description

Added support for VA-API quality preset in Mesa >= 22.3. https://gitlab.freedesktop.org/mesa/mesa/-/commit/a727ec83ba01776e9c6f61c912c4caac280e968e

Motivation and Context

Better encoding quality on AMD cards on Linux.

How Has This Been Tested?

On ArchLinux (mesa 22.3.1, ffmpeg 5.1.2).

Types of changes

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

Checklist:

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

Screenshot:

[tytan652]

~~Screenshot of the UI change are missing.~~

[tytan652]

On ArchLinux with mesa-git.

Please test on a real release not a git package.

[nowrep]

Done.