This module exposes the platform utils defined in the GPU module in C.
This will be useful for porting existing code with `bgl` to `gpu`.
Reviewed By: fclem, brecht, campbellbarton
Maniphest Tasks: T80730
Part of D11147
Part of the vulkan implementation T68990.
Pretty straight forward. Just move the GL code inside the GLBackend and
make the GPUPlatformGlobal a class object.