[PassBuilder] Use loop-mssa for licm

[PassBuilder] Use loop-mssa for licm

Currently specifying -licm or -passes=licm will implicitly create
-passes=loop(licm). This does not match the intended default (used
by the legacy PM and by the default pipeline) of using the
MemorySSA-based LICM implementation. As I plan to drop the non-MSSA
implementation, this will stop working entirely...

This special-cases licm to create a loop-mssa manager instead. At
this point it's still possible to use -passes='loop(licm)' to opt
into the AST-based implementation.

Differential Revision: https://reviews.llvm.org/D108155