fix: Color conversion for Wayland compositors that use non-linear pixel formats

[gmbeard]

Implements a simple pixel shader pipeline to perform color conversion on Wayland

Video frame times remain on par with expected performance on my setup, with the vast majority of frames captured in under 2ms...

TODOs:

• [x] Code tidy-up
• [x] Check Clang builds
• [x] Static analysis warnings / Sanitizer checks
• [x] Check for performance regressions
• [x] Squash commits

fixes #39