[clang-tidy] prevent generated checks from triggering assertions on anonymous functions

Skeleton checks generated by clang-tidy add_check.py cause assertions to fail when run over anonymous functions(lambda functions). This patch introduces an additional check to verify that the target function is not anonymous before calling getName().
The code snippet from the [[ https://clang.llvm.org/extra/clang-tidy/Contributing.html | clang-tidy tutorial  ]]is also updated.

Reviewed By: alexfh, DavidTruby

Differential Revision: https://reviews.llvm.org/D85218