The patch also does some cleanup on the interface of the entry
points from TargetFinder into the heuristic resolution code.
Since the heuristic resolver is created in a place where the
ASTContext is available, it can store the ASTContext and the
NameFactory hack can be removed.
Differential revision: https://reviews.llvm.org/D92290
Many useful signals can be derived from a valid AST which is regularly updated by
the ASTWorker. `runWithPreamble` does not have access to the ParsedAST
but it can be provided access to some signals derived from a (possibly
stale) AST.
Differential Revision: https://reviews.llvm.org/D94424