[refactoring] Introduce a generator of support functions
[refactoring] Introduce a generator of support functions

Summary: This diff is a minor refactoring that introduces a generator of support functions (`Language.t -> support`) for each checkers. There were several number of pre-defined support functions, but they will be more complicated later when we support more languages.

Reviewed By: ezgicicek, ngorogiannis

Differential Revision: D33062517

fbshipit-source-id: 258fa35674

facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer