[LAA] Change to function analysis for new PM.

At the moment, LoopAccessAnalysis is a loop analysis for the new pass
manager. The issue with that is that LAI caches SCEV expressions and
modifications in a loop may impact SCEV expressions in other loops, but
we do not have a convenient way to invalidate LAI for other loops
withing a loop pipeline.

To avoid this issue, turn it into a function analysis which returns a
manager object that keeps track of the individual LAI objects per loop.

Fixes #50940.

Fixes #51669.

Reviewed By: aeubanks

Differential Revision: https://reviews.llvm.org/D134606