[clang] [HLSL] Add support for the HLSL matrix type (PR #159446)

[Chris B via cfe-commits]

https://github.com/llvm-beanz commented:

One thing we didn't do with the vector alias that we should do for the `matrix` one is add a concept requirement that the dimensions be in the range [1,4].

We removed the restriction on vector length in HLSL, but I don't believe we have any plans to do the same for matrices.

https://github.com/llvm/llvm-project/pull/159446