[clang-tidy] Migrate objc-forbidden-subclassing to use isDerivedFrom 🚛

Summary:
This migrates objc-forbidden-subclassing to `isDerivedFrom` as it now
supports matching Objective-C interface declarations.

Test Notes:
Ran clang tools tests.

Reviewers: aaron.ballman, gribozavr

Reviewed By: aaron.ballman

Subscribers: xazax.hun, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D66269

llvm-svn: 369076