[clangd] Improve heuristic resolution of dependent types in TargetFinder

 * Try to apply heuristic resolution recursively to the base
   expression of a CXXDependentScopeMemberExpr.

 * Try to apply heuristic resolution recursively to the callee
   expression in a call expression.

Fixes https://github.com/clangd/clangd/issues/441

Subscribers: ilya-biryukov, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D82739