[PM] Port LoopDataPrefetch to new pass manager

Summary:
Refactor the existing support into a LoopDataPrefetch implementation
class and a LoopDataPrefetchLegacyPass class that invokes it.
Add a new LoopDataPrefetchPass for the new pass manager that utilizes
the LoopDataPrefetch implementation class.

Reviewers: mehdi_amini

Subscribers: sanjoy, mzolotukhin, nemanjai, llvm-commits

Differential Revision: https://reviews.llvm.org/D23483

llvm-svn: 278591