Add observers to WebXRCamera when a rotation is performed

[yuripourre]

Add observables onBeforeCameraTeleportRotation and onAfterCameraTeleportRotation to WebXRMotionControllerTeleportation.

npm run format:fix

[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/14660/merge

Test environment:
https://babylonsnapshots.z22.web.core.windows.net/refs/pull/14660/merge/index.html

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https://babylonsnapshots.z22.web.core.windows.net/refs/pull/14660/merge/index.html#WGZLGJ#4600

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[RaananW]

I made the mistake of putting the first observable on the camera and not on the feature itself. There is no reason for it to be on the camera. Let's learn from (my) mistakes and move the observables to the feature class

[yuripourre]

@RaananW Done!

[RaananW]

Thanks! this is great. I guess we can add a proxy from the teleportation to the camera's observable and mark it deprecated on the camera. But this is a very low priority.

[yuripourre]

@RaananW that would be great. It crossed my mind to do that but I am focusing on other improvements currently, like adding a BVH file loader.