Support GPU format/colourspace conversion

[dsaedtler]

Description

Extends GPU scaling to also handle colourspace or format conversions to enable shared-texture encoding with heterogenous output formats.

Note: Includes #11336

Motivation and Context

#11336 falls back to shared memory encoders, which are less efficient, this aims to fix that by extending the conversion capabilities.

In theory this would also allow recording HDR locally and streaming SDR, among other use cases that people might have.

Will need some additional discussion related to function naming and implemenation of the new texture availability check.

How Has This Been Tested?

Streamed to Twitch while recording 444 locally as well as streaming SDR while recording HDR locally.

Also currently only fully implemented for NVENC, will need AMFQSV as well.

Types of changes

• Tweak (non-breaking change to improve existing functionality)
• Performance enhancement (non-breaking change which improves efficiency)

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.