ScalarizeMaskedMemIntrinsic is currently a codeGen level pass. The pass is
actually operating on IR level and does not use any code gen specific passes.
It is useful to move it into transforms directory so that it can be more widely
used as a mid-level transform as well (apart from usage in codegen pipeline).
In particular, we have a usecase downstream where we would like to use this pass
in our mid-level pipeline which operates on IR level.
The next change will be to add support for new PM.