[WIP] Fixing DLSS and TAU to be compatible with Blitter and Custom post process

[kecho]

Purpose of this PR

Fixing issues with custom post process, and HDCore Blit utility. This will make DLSS and TAU compatible wtih the blitter & custom post process.
Issue: Because the upscaled color has its own resolution, and there is a global RT handle scale state, Ive decided to make the color texture explicit in size of DLSS and TAU. This will make the Blitter work. Custom post processes still need to use _PostProcessSize in order to scale the color.

There will be some performance cost likely, 1 extra target, however because this resolution is immutable (the final resolution) I dont suspect there will be issues.

This PR will require a full pass from QA, and bloom + inspection on all post processes is still pending.

https://fogbugz.unity3d.com/f/cases/1352407/

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Testing status

Pending.

[github-actions]

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