This remove the complexity of queriying the locations at runtime and
allows for more performance and upfront binding specifications.
The benefit of doing everything at creation time is that we can assign binding
points in a predictable order which is going to be somewhat the same for
every similar shader.
This also rewrite GPU_vertformat_from_shader to not use shaderface.
This is to keep the shaderface simple. If it becomes necessary to not query
the shader after creation (i.e: vulkan?) we could just create the vert
format in advance at compilation for PyGPU shaders.
Reviewed By: brecht
Differential Revision: https://developer.blender.org/D7879
cecda64e2e