[Matrix] Add tests identifying GVN and DSE opportunities for matrix store / load intrinsics (#163573)
This patch adds several tests identifying potential opportunities for
eliminating dead stores and redundant loads when using the
`llvm.matrix.column.major.store.*` and `llvm.matrix.column.major.load.*`
intrinsics.
PR: https://github.com/llvm/llvm-project/pull/163573