With the compute pipeline calculation can be offloaded to the GPU.
This patch only adds the framework for compute. So no changes for users at
this moment.
NOTE: As this is an OpenGL4.3 feature it must always have a fallback.
Use `GPU_compute_shader_support` to check if compute pipeline can be used.
Check `gpu_shader_compute*` test cases for usage.
This patch also adds support for shader storage buffer objects and device only
vertex/index buffers.
An alternative that had been discussed was adding this to the `GPUBatch`, this
was eventually not chosen as it would lead to more code when used as part of a
shading group. The idea is that we add an `eDRWCommandType` in the near
future.
Reviewed By: fclem
Differential Revision: https://developer.blender.org/D10913
