Rename DescribeHeapAddress to DescribeAddressIfHeap and split it into a...

Rename DescribeHeapAddress to DescribeAddressIfHeap and split it into a function to get all the information about the address, and one to print it.

Summary:
Replacement for part of D23518
This deals with heap addresses, and renames DescribeHeapAddress.
Requires D23520, which moves code around to make it accessible in asan_describers.cc (and still accessible in asan_report.cc if needed).

Reviewers: kcc, samsonov

Subscribers: kubabrecka, llvm-commits

Differential Revision: https://reviews.llvm.org/D23569

llvm-svn: 278917