[VFX] Mobile fixes

[julienf-unity]

Purpose of this PR

Some mobile fixes for VFX Graph:

• https://fogbugz.unity3d.com/f/cases/1348666/
• https://fogbugz.unity3d.com/f/cases/1149057/

This is a first pass, and other fixes are required for mobile devices (in particular some C++ changes)

For 1348666, I've checked with @hkr, and decided to guard functions using cubemap arrays between SHADER_AVAILABLE_CUBEARRAY check. They may revert to old behavior possibly at some point.

For 1149057, The issue is caused by driver bug for certain integer instructions (in this case, it's with bitFieldExtract). I've worked around them by using float instruction instead.
I've tested all outputs: There's still a potential issue with cube output uv computation, but as it is an experimental feature that has other bugs, I don't have an immediate fix for that (and not sure if it's worth it anyway)

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Testing status

Tested locally on Oculus Quest 2 with GLES3.1 (Vulkan does not exhibit the issue)

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Comments to reviewers

Notes for the reviewers you have assigned.

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[gabrieldelacruz]

Looks good!

[VitaVFX]

Hey @julienf-unity! Here's the WIP Test Doc. Main issue of extended particles on Android is fixed, it haven't occured on any of the devices during first QA pass. Whew!

Speaking further, some of the issues are already summarized (included minor and major issues) with provided reproduction and can be worked on. Some of them still need some attention thus dropped some questions in the doc. (Figured out answers (I think)).

Also, if there's anything I can do to make the investigation on your side easier, let me know.

[julienf-unity]

Hey @julienf-unity! Here's the WIP Test Doc. Main issue of extended particles on Android is fixed, it haven't occured on any of the devices during first QA pass. Whew!

Speaking further, some of the issues are already summarized (included minor and major issues) with provided reproduction and can be worked on. Some of them still need some attention thus dropped some questions in the doc. (Figured out answers (I think)).

Also, if there's anything I can do to make the investigation on your side easier, let me know.

Yes this is what this PR is fixing. Of course there's still lots of other issues but it shouldnt block the PR. If the "extended particle" fix is verified, I would like to merge it before branching off.

[VitaVFX]

Approving as the main issue is fixed, other issues will be looked into in another fix pass.

[julienf-unity]

#5582 must be backported at the same time as this one