Update the `ShaderCompilerGeneric` to support deferred compilation
using the batch compilation API, so we can get rid of
`drw_manager_shader`.
This approach also allows supporting non-blocking compilation
for static shaders.
This shouldn't cause any behavior changes at the moment, since batch
compilation is not yet used when parallel compilation is disabled.
This adds a `GPUWorker` and a `GPUSecondaryContext` as an easy to use
wrapper for managing secondary GPU contexts.
(Part of #133674)
Pull Request: https://projects.blender.org/blender/blender/pulls/136518
a5ed5dc4bf