[clang] [llvm] [Matrix] Implement matrix support for the `abs` intrinsic (PR #227131)

[Kaitlin Peng via cfe-commits]

kmpeng wrote:

The XPASSing tests in `HLSL-Tests` are expected - this missing implementation is why the `abs` matrix tests were XFAILed. Will remove the XFAILs once this implementation goes in.

https://github.com/llvm/llvm-project/pull/227131