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

[Kaitlin Peng via cfe-commits]

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+// RUN: %clang_cc1 -finclude-default-header -x hlsl -triple \
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kmpeng wrote:

I don't really think testing all these types + sizes is necessary - just `int`/`uint`/`half` should cover the three distinct `abs` paths. I tested all of them to mirror the scalar/vector `abs.hlsl` test and other matrix tests which test all types + sizes the intrinsic supports, but I'm open to changing it.

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