[mlir][Transform] Introduce nvgpu transform extensions

[mlir][Transform] Introduce nvgpu transform extensions

Mapping to NVGPU operations such as mma.sync with mixed precision and ldmatrix with transposes and
various data types involves complex matchings from low-level IR.
This is akin to raising complex patterns after unnecessarily having lost structural information.
To avoid such unnecessary complexity, introduce a direct mapping step from a matmul on memrefs
to distributed NVGPU vector abstractions.
In this context, mapping to specific mma.sync operations is trivial and consists in simply
translating the documentation into indexing expressions.

Correctness is demonstrated with an end-to-end integration test.

Differential Revision: https://reviews.llvm.org/D153420