[mlir] Extract forall_to_for logic into reusable function and add pass (#89636)

This PR extracts the existing `scf.forall` to `scf.for` conversion logic
inside a transform op (https://github.com/llvm/llvm-project/pull/65474)
into a standalone function which can be used in other transformations
and adds a `scf-forall-to-for` pass.