[llvm] [Matrix] Add tests identifying GVN and DSE opportunities for matrix store / load intrinsics (PR #163573)

[Florian Hahn via llvm-commits]

================
@@ -0,0 +1,53 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: opt -passes=dse -S < %s | FileCheck %s
----------------
fhahn wrote:

```suggestion
; RUN: opt -passes=dse -S %s | FileCheck %s
```

https://github.com/llvm/llvm-project/pull/163573