Implement hook for checking switch lint

Summary:
We want to use it for `yield` and `invariant_violation()` which throws.
Having node instead of token would be better but this would be enough.

Test Plan: Implemented a hook in FB repo and added a test case there.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D4821