Some fixes for 6DoF

[RaananW]

• isNearGrabbable is now set on the mesh and its children (will enable grabbing glTFs as well)
• If the attached controller changes in XR and the last controller had a pointer down triggered, a pointer up event will trigger (caused an issue with 6DoF)
• Multipointer in WebXR is disabled (temporary) until an issue with touching multipointers will be solved.
• Docs updated for more clarity
• XR evets are treated the same in 6DoF, meaning a remote controller can now rotate a model when using 6DoF behavior.

[bjsplat]

Please make sure to label your PR with "bug", "new feature" or "breaking change" label(s).
To prevent this PR from going to the changelog marked it with the "skip changelog" label.

[bjsplat]

Snapshot stored with reference name:
refs/pull/14911/merge

Test environment:
https://babylonsnapshots.z22.web.core.windows.net/refs/pull/14911/merge/index.html

To test a playground add it to the URL, for example:

https://babylonsnapshots.z22.web.core.windows.net/refs/pull/14911/merge/index.html#WGZLGJ#4600

Links to test babylon tools with this snapshot:

https://playground.babylonjs.com/?snapshot=refs/pull/14911/merge
https://sandbox.babylonjs.com/?snapshot=refs/pull/14911/merge
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To test the snapshot in the playground with a playground ID add it after the snapshot query string:

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[bjsplat]

Visualization tests for WebGPU (Experimental)
Important - these might fail sporadically. This is an optional test.

https://babylonsnapshots.z22.web.core.windows.net/refs/pull/14911/merge/testResults/webgpuplaywright/index.html

[bjsplat]

WebGL2 visualization test reporter:

https://babylonsnapshots.z22.web.core.windows.net/refs/pull/14911/merge/testResults/webgl2playwright/index.html

[matthargett]

Multipointer in WebXR is disabled (temporary) until an issue with touching multipointers will be solved.

Is there an issue filed to track this issue? Does it need an explicit mention in the release notes?

[RaananW]

Multipointer in WebXR is disabled (temporary) until an issue with touching multipointers will be solved.

Is there an issue filed to track this issue? Does it need an explicit mention in the release notes?

I will be working on that tomorrow, but if I can't fully debug and fix it tomorrow we will keep it disabled for 7.0. I will either fix it or create an issue to track it.

[bjsplat]

Visualization tests for WebGPU (Experimental)
Important - these might fail sporadically. This is an optional test.

https://babylonsnapshots.z22.web.core.windows.net/refs/pull/14911/merge/testResults/webgpuplaywright/index.html

[RaananW]

Multipointer in WebXR is disabled (temporary) until an issue with touching multipointers will be solved.

Is there an issue filed to track this issue? Does it need an explicit mention in the release notes?

Issue for tracking - #14914