Allow lights to change without shader recompilation

[matanui159]

This is just the groundwork so far, making all the lights share the same uniforms. A lot isn't supported right now, notably:

• PBR materials
• area lights (need to figure out if I can have a default for the LTC textures? or maybe I just add them to the "not dynamic" list)
• all the defines are still added and recompilation occurs, need to reduce that down
• sort the lights that can be dynamic after the lights that can't (for example a sun light with shadows should always the first light)
• filter out lights that are both dynamic and too far away (might be seperate PR?)

I don't currently plan to make these dynamic (notably since I assume there won't be many lights with these, and also I feel like it would add too much branching in the shader):

• Shadows
• lights with falloff other than FALLOFF_DEFAULT (maybe an option could be added to set the default falloff?)

[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/16854/merge

Test environment:
https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16854/merge/index.html

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

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16854/merge/index.html#WGZLGJ#4600

Links to test babylon tools with this snapshot:

https://playground.babylonjs.com/?snapshot=refs/pull/16854/merge
https://sandbox.babylonjs.com/?snapshot=refs/pull/16854/merge
https://gui.babylonjs.com/?snapshot=refs/pull/16854/merge
https://nme.babylonjs.com/?snapshot=refs/pull/16854/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/16854/merge#BCU1XR#0

[bjsplat]

WebGL2 visualization test reporter:

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16854/merge/testResults/webgl2playwright/index.html

[bjsplat]

Visualization tests for WebGPU

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16854/merge/testResults/webgpuplaywright/index.html

[bjsplat]

WebGL2 visualization test reporter:

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16854/merge/testResults/webgl2playwright/index.html

[bjsplat]

Visualization tests for WebGPU

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16854/merge/testResults/webgpuplaywright/index.html

[bjsplat]

WebGL2 visualization test reporter:

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16854/merge/testResults/webgl2playwright/index.html

[bjsplat]

Visualization tests for WebGPU

https://snapshots-cvgtc2eugrd3cgfd.z01.azurefd.net/refs/pull/16854/merge/testResults/webgpuplaywright/index.html