Fix LightOccluder2D SDF Collision Enable/Disable

[cosparks]

SDF collision enabled parameter wasn't being assigned to anything so disabling SDF collisions on LightOccluder2D had no effect.

With this change, unchecking SDF Collisions will actually disable collisions between gpu particles and light occluders.

closes #90882

[cosparks]

There should be a hold on this as setting LightOccluderInstance::enabled to false also disables shadow casting, which I would imagine isn't the desired behaviour.

On the other hand, setting LightOccludeInstance::sdf_collision to false has no effect, so the issue probably lies somewhere deeper than in RendererCanvasCull::canvas_light_occluder_set_as_sdf_collision

I've updated the PR

[cosparks]

@reduz I saw that you implemented sdf for 2d shaders.

Was the original idea that LightOccluder2Ds with sdf_collision set to false wouldn't be drawn to the sdf texture? If you could take a look at this that would be awesome.

Edit: I just looked at the documentation for LightOccluder2D and it seems that this is the case, so this is probably the right fix.

[clayjohn]

Looks great! The final step before merging is to squash all the commits together so that the whole PR only contains 1 big commit with all your changes. We like to merge one commit at a time to keep the git history clean and navigable.

If you don't know how to do that, we have a helpful tutorial in the official documentation https://docs.godotengine.org/en/latest/community/contributing/pr_workflow.html#the-interactive-rebase

[cosparks]

Cool! I just squashed my commits. Thanks for linking the docs.

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉