[erl-frontend] Organize Erlang Pulse models into submodules
[erl-frontend] Organize Erlang Pulse models into submodules

Summary: Some organization for better readability.

Reviewed By: jvillard

Differential Revision: D33545556

fbshipit-source-id: 865f044a63

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