[analyzer] Add support for CXXInheritedCtorInitExpr.

So far we've been dropping coverage every time we've encountered
a CXXInheritedCtorInitExpr. This patch attempts to add some
initial support for it.

Constructors for arguments of a CXXInheritedCtorInitExpr are still
not fully supported.

Differential Revision: https://reviews.llvm.org/D74735