[llvm] [mlir] [mlir][transforms]-Extract dead code elimination util (PR #124606)

[Amir Bishara via llvm-commits]

amirBish wrote:

@River707 Thanks for the quick reply, I didn't know about the region simplification although i have searched a lot. surely will use the `runRegionDCE` method :)

So why not running the applyDeadCodeEliminationOp transform op using this method? why have a duplicated utils to do DCE?

https://github.com/llvm/llvm-project/pull/124606