[Utils] Check function attributes in update_test_checks

Summary:
This introduces new flag to the update_test_checks and
update_cc_test_checks that allows for function attributes
to be checked in a check-line. If the flag is not set,
the behavior should remain the same.

Reviewers: jdoerfert

Subscribers: arichardson, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D83629