Mesh: fix LOD management

[Popov72]

While working on the frame graph, I noticed that we had a problem with LOD management when using custom render target textures.
Take this PG:

https://playground.babylonjs.com/#WSWPUJ#1

The large sphere comes from the main rendering, which uses a camera located at a distance of 10 from the sphere.
The small sphere comes from a render target texture (RTT), which is displayed on a vertical plane and uses a camera located at a distance of 30 from the sphere.
A LOD (box) has been defined for the sphere, at a distance of 15.
We should therefore see a box instead of the small sphere, as 30 > 15.

What we see	What we should see

This doesn't work because the LOD is calculated for the main camera and reused for all custom RTTs.
The PR updates the LOD management by storing the LOD per camera.
In addition, I've introduced a cameraForLOD property in ObjectRenderer / RenderTargetTexture, because we may want to use a LOD for a camera that is different from ObjectRenderer.activeCamera (think of rendering from a light: the LOD should be retrieved from the main camera, not from the light's point of view). If not supplied, cameraForLOD=activeCamera to maintain backward compatibility.

Other changes in this PR are frame graph related:

• added the camera entry to the shadow generator frame graph task. I hadn't originally added this entry because we didn't need it for rendering, but we do need it to retrieve a correct LOD (which is also why I added the new ObjectRenderer.cameraForLOD property).
• fixed a bug with DoF task in WebGL
• added visualization tests

Other changes:

• fixed a state problem where the current frame buffer was not reset to the correct value at the end of createMultipleRenderTarget.
• fixed shadowMap.customIsReadyFunction to correctly check readiness when ObjectRenderer.isReady is called.
• improved debugging by updating engine render pass names when ObjectRenderer.name is updated

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[bjsplat]

Snapshot stored with reference name:
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Visualization tests for WebGPU (Experimental)

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[bjsplat]

WebGL2 visualization test reporter:

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