Add GraphicsSystemValues.test for graphics-stage system-value semantics

[EmilioLaiso]

Based on top of: #1127
Better diff: Traverse-Research/offload-test-suite@front-face-ccw...Traverse-Research:offload-test-suite:graphics-semantics

Adds a new test that bundles every per-pixel, observable graphics-stage system-value semantic the framework can express today into one shader pass.
Modeled on the existing ComputeSystemValues.test.
Covers SV_VertexID, SV_PrimitiveID, SV_IsFrontFace, and SV_POSITION pass-through.

[manon-traverse]

I like the things we are testing, I am just wondering if it is better from a compiler developer's point of view if we have a test for each one of these or have more elements mixed in one test like we did here.

[EmilioLaiso]

I like the things we are testing, I am just wondering if it is better from a compiler developer's point of view if we have a test for each one of these or have more elements mixed in one test like we did here.

Considering ComputeSystemValues.test exists, I think it's ok for this pass to also test multiple semantics at the same time.
SV_POSITION is basically tested in every other graphics test as well, so it's really only testing SV_VertexID, SV_PrimitiveID and SV_IsFrontFace. I don't see the point of adding 3 identical tests for some very fundamental semantics.