[Flang] Move genMinMaxlocReductionLoop to Transforms/Utils.cpp (#81380)

This is one option for attempting to move genMinMaxlocReductionLoop to a
better location. It moves it into Transforms and makes HLFIRTranforms
depend upon FIRTransforms.

It passes a build locally, both with and without -DBUILD_SHARED_LIBS,
and does OK on the windows CI.