Convert HDRP tests to use MockHMD for XR

[fabien-unity]

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Purpose of this PR

• refactor XR tests to be able to use MockHMD and the full XR SDK path
• disable some tests until further investigation

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Testing status

Yamato run is similar to master (mac is failing).

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Comments to reviewers

There's a lot a files but it's mostly boilerplate and Yamato configuration

[DennisDeRykeUnity]

I approve.

For this PR I am only comparing master versus the dev branch for Nightly HDRP on Yamato, because the code changes are isolated to:

• com.unity.render-pipelines.high-definition
• com.unity.testing.hdrp
• HDRP-based test projects
• HDRP-related Yamato configuration

• PR dev branch:
  https://yamato.cds.internal.unity3d.com/jobs/902-Graphics/tree/tests%252Fxr%252Fconvert-to-mockhmd-2/.yamato%252Fall-hdrp.yml%2523Nightly_HDRP_trunk/4815973/job

• master:
  https://yamato.cds.internal.unity3d.com/jobs/902-Graphics/tree/master/.yamato%252Fall-hdrp.yml%2523Nightly_HDRP_trunk/4819543/job

Some observations:

1. Nightly HDRP contains the same number of pipelines for both dev branch and master; both contain six XR pipelines.

2. In Nightly HDRP for master HDRP_DXR on Win_DX12_playmode_XR failed due to a single inconclusive test, HDRP_GraphicTestRunner.5006_PathTracing_DoF, which is not present in the dev branch results.

3. For the dev branch all XR pipelines in Nightly HDRP passed.

4. In Nightly HDRP the only failed pipeline for the dev branch was HDRP on OSX_Metal_playmode. This pipeline failed on both master and the dev branch with 26 failed tests.