[mlir] Add base class for GpuKernelToBlobPass

Instead of configuring kernel-to-cubin/rocdl lowering through callbacks, introduce a base class that target-specific passes can derive from.

Put the base class in GPU/Transforms, according to the discussion in D98203.

The mlir-cuda-runner will go away shortly, and the mlir-rocdl-runner as well at some point. I therefore kept the existing code path working and will remove it in a separate step.

Depends On D98168

Reviewed By: herhut

Differential Revision: https://reviews.llvm.org/D98279