[PM] Complete the cross-layer interfaces with a Module-to-Function
proxy. This lets a function pass query a module analysis manager.
However, the interface is const to indicate that only cached results can
be safely queried.

With this, I think the new pass manager is largely functionally complete
for modules and analyses. Still lots to test, and need to generalize to
SCCs and Loops, and need to build an adaptor layer to support the use of
existing Pass objects in the new managers.