Since Embree v3.13.0 supports AARCH64, switch back to the
official repo instead of using Embree-aarch64.
`thirdparty/embree/patches/godot-changes.patch` should now contain
an accurate diff of the changes done to the library.
Added an occlusion culling system with support for static occluder meshes.
It can be enabled via `Project Settings > Rendering > Occlusion Culling > Use Occlusion Culling`.
Occluders are defined via the new `Occluder3D` resource and instanced using the new
`OccluderInstance3D` node. The occluders can also be automatically baked from a
scene using the built-in editor plugin.
