[PDB] Extend IPDBSession's interface to retrieve frame data

[PDB] Extend IPDBSession's interface to retrieve frame data

Summary:
This patch just extends the `IPDBSession` interface to allow retrieving
of frame data through it, and adds an implementation over DIA. It is needed
for an implementation (for now with DIA) of the conversion from FPO programs
to DWARF expressions mentioned in D53086.

Reviewers: zturner, asmith, rnk

Reviewed By: asmith

Subscribers: mgorny, aprantl, JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D53324

llvm-svn: 344886