[mlir][gpu][mlir-cuda-runner] Refactor ConvertKernelFuncToCubin to be generic.

Make ConvertKernelFuncToCubin pass to be generic:

- Rename to ConvertKernelFuncToBlob.
- Allow specifying triple, target chip, target features.
- Initializing LLVM backend is supplied by a callback function.
- Lowering process from MLIR module to LLVM module is via another callback.
- Change mlir-cuda-runner to adopt the revised pass.
- Add new tests for lowering to ROCm HSA code object (HSACO).
- Tests for CUDA and ROCm are kept in separate directories.

Differential Revision: https://reviews.llvm.org/D80142