HQAA: making mashed potatoes out of SMAA and FXAA

# HQAA

I don't feel that this is ready to be called a v1.0 shader yet as it's still potentially subject to significant change, but it compiles and runs without warnings or errors as it stands, and seems to provide at least a modest improvement over either single method. Feedback very welcome.

Version 0.2 just pushed. Improved the flow of order of operations in the shader and the configuration used for the FXAA component to eliminate a problem with false positive aliasing artifacts.

Version 0.3 pushed. Now includes a baked-in (weak) CAS sharpening pass which, like FXAA and SMAA, is computed from the shader settings UI to counteract blurring caused. Additional post-process sharpening will still be desirable in most cases as this final pass is only calibrated to counteract blurring from the anti-aliasing blending.

Here's a quick tri-comparison shot of HQAA 0.3 in Satisfactory Experimental (update 5) under DX12 engine power with internal anti-aliasing in the Unreal engine explicitly disabled.

HQAA OFF
HQAA Subpixel Effects = 0.0
HQAA Subpixel Effects = 1.0