Ensure RenderLayers is a Component on every ExtractedLight and its ShadowView/ExtractedView

[kfc35]

Objective

Fixes #24792

queue_shadows() currently queues shadows erroneously because the view light entity never has the RenderLayers component correctly attached. This not only affects directional lights as described in the issue, but all the light types.

Solution

• Ensure all four types of lights (point, spot, directional, rect) have their render layers extracted (or set to the default layer if not specified).
• Ensure that the filtering in queue_shadows() actually works with render layers by ensuring that the light entity always has render layers specified. (rect light is an exception since it doesn’t have shadows currently)
• I standardized the way RenderLayers is attached to extracted lights — I figured that, since it’s a component, it should be attached separately (i.e. not set directly to the extracted structure a la ExtractedDirectionalLight. I remove the RenderLayers from that component.).

Note that this issue/fix is separate from the problem described in #23264. This only ensures the light <-> mesh render layer relationship is respected when queueing shadows. This doesn’t fix anything about the light illuminating the wrong meshes and does not touch any shader code.

Testing

• The minimal reproduction example in Directional lights shadows not rendered for non default render layers #24792 is fixed
• Ran the pcss example and changed between the lights and rect_light just to make sure there isn't a regression.

[Zeophlite]

I think this is a better separation of concerns