[clang-tidy] Aliasing: Add support for captures.

The utility function clang::tidy::utils::hasPtrOrReferenceInFunc() scans the
function for pointer/reference aliases to a given variable. It currently scans
for operator & over that variable and for declarations of references to that
variable.

This patch makes it also scan for C++ lambda captures by reference
and for Objective-C block captures.

Differential Revision: https://reviews.llvm.org/D96215