The PBVHFrustumPlanes `struct` is a thin wrapper around a collection of `float4`s, each representing a plane. This commit removes this concept in favor of static sized `std::array<float4, 6>` to avoid errors when indexing into the collection and uses `Span`s when performing tests against AABBs Pull Request: https://projects.blender.org/blender/blender/pulls/129609