Implemented Snapdragon Game Super Resolution

[Torgo13]

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Purpose of this PR

Snapdragon™ Game Super Resolution is a lightweight anti-aliasing and upscaling solution optimised for mobile devices such as Adreno™ GPU hardware. Compared to AMD FidelityFX™ Super Resolution 1.0, it performs both upscaling and sharpening in a single GPU shader pass.

https://github.com/SnapdragonStudios/snapdragon-gsr

This is a port of the SGSR sample to the Universal Render Pipeline. It adds a new upscaling filter to the UniversalRenderPipelineAsset and is applied when the render scale is less than 1.

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Testing status

I have tested SGSR on an AMD 680M, an Adreno 650, an Apple M1 8-Core GPU and an Apple A13 Bionic GPU. I have also tested it in Unity 2022.3.28f1 with URP 14.0.11.

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Comments to reviewers

Areas for improvement include moving the added functions in FinalPost.shader to a separate header file like in the official sample, as well as exposing the three options in sgsr_mobile.hlsl to the editor, allowing SGSR to be more effective for VR use.

I will follow up this draft with a commit updating the documentation and changelog.