[mlir][AMDGPU] Define wrappers for WMMA matrix ops

Wave Matrix Multiply Accumulate (WMMA) is the instruction to accelerate
matrix multiplication on RDNA3 architectures.  LLVM already provides a
set of intrinsics to generate wmma instructions. This change uses those
intrinsics to enable the feature in MLIR.

Reviewed By: krzysz00

Differential Revision: https://reviews.llvm.org/D152451