Viewer: Add shadow support

[alexandremottet]

In the viewer, add the support for :

• shadow map,
• ibl shadows
• shadow quality selection normal, high

For now, ibl shadows are dissabled for meshes that have animations in WebGPU even if the animation is paused as there is some issues.

The auto shadow selection will come in another PR.
The placement of the light will come in another PR.

Edit from @ryantrem: from local testing, these are the remaining issues I'm seeing:

• Shadow map shadows don't work when "statically" enabled (e.g. <babylon-viewer shadow-quality="normal">).
• IBL shadows do not update when an animation is running. I assume this is not supported in IBL shadows, but if that is the case, should we disallow IBL shadows for animated models?
• IBL shadows seem to get into a bad state after I load a few different models. This can be reproed in the Viewer test app by just dragging and dropping a sequence of models with IBL shadows enabled. After a few models, I start seeing wrong shadows or significant rendering artifacts. I'm not sure if there is a missing accumulator reset, or if this is a bug in IBL shadows or what.

[bjsplat]

WebGL2 visualization test reporter:

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16459/merge/testResults/webgl2playwright/index.html

[bjsplat]

Reviewer - this PR has made changes to one or more package.json files.

[bjsplat]

Visualization tests for WebGPU

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16459/merge/testResults/webgpuplaywright/index.html

[bjsplat]

WebGL2 visualization test reporter:

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16459/merge/testResults/webgl2playwright/index.html

[bjsplat]

Reviewer - this PR has made changes to one or more package.json files.

[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]

Reviewer - this PR has made changes to one or more package.json files.

[bjsplat]

Snapshot stored with reference name:
refs/pull/16459/merge

Test environment:
https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16459/merge/index.html

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

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16459/merge/index.html#WGZLGJ#4600

Links to test babylon tools with this snapshot:

https://playground.babylonjs.com/?snapshot=refs/pull/16459/merge
https://sandbox.babylonjs.com/?snapshot=refs/pull/16459/merge
https://gui.babylonjs.com/?snapshot=refs/pull/16459/merge
https://nme.babylonjs.com/?snapshot=refs/pull/16459/merge

To test the snapshot in the playground with a playground ID add it after the snapshot query string:

https://playground.babylonjs.com/?snapshot=refs/pull/16459/merge#BCU1XR#0

[bjsplat]

WebGL2 visualization test reporter:

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16459/merge/testResults/webgl2playwright/index.html

[bjsplat]

Visualization tests for WebGPU

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16459/merge/testResults/webgpuplaywright/index.html