[clang] [Matrix] Add a row\col major toggle in the clang driver (PR #167628)

[Farzon Lotfi via cfe-commits]

farzonl wrote:

@cofibrant I removed the use of the flags llvm needs for the lower-matrix-intrinsics pass. I think that should have addressed your concerns so for now this is a flag that does nothing, but my follow on prs usage of the flag will have a clear distinction between 1.  layout of matrix types in memory and 2. the layout used by LLVM when lowering matrix intrinsics. 

We can revist merging this concept later when the `llvm.matrix.row.major.load` and `llvm.matrix.row.major.store` intrinsics are implemented if that is prefered.

In anycase I'll wait for @fhahn.

https://github.com/llvm/llvm-project/pull/167628