[mlir] [MLIR][Linalg] Add aggregate ops decomposition pass and softmax decom… (PR #97582)

[Andrzej Warzyński]

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+// RUN: mlir-opt %s -split-input-file -linalg-decompose-named-ops | FileCheck %s
+// RUN: mlir-opt %s -split-input-file -linalg-decompose-named-ops -linalg-generalize-named-ops | FileCheck %s --check-prefix=GENERALIZECHECK
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banach-space wrote:

[nit] With more than one CHECK prefix, you can drop `CHECK` (which is just noise IMHO), and leverage the prefixes to better document what's tested:
```
// RUN: mlir-opt %s -split-input-file -linalg-decompose-named-ops | FileCheck %s -check-prefix=DECOMPOSED
// RUN: mlir-opt %s -split-input-file -linalg-decompose-named-ops -linalg-generalize-named-ops | FileCheck %s --check-prefix=GENERALIZED
```

I am also making the suggestion to make sure that my understanding is correct.

https://github.com/llvm/llvm-project/pull/97582