[Printer] Exposing some layout utils
[Printer] Exposing some layout utils

Summary: Exposing utilities in `js_layout_generator.ml` to be used by the normalized type printer.

Reviewed By: mroch

Differential Revision: D6913918

fbshipit-source-id: a87f8158dc3584363cb771c352b52aa993bbece8

samwgoldman/flow,gabelevi/flow,JonathanUsername/flow,mroch/flow,facebook/flow,facebook/flow,claudiopro/flow,nmote/flow,samwgoldman/flow,AgentME/flow,popham/flow,samwgoldman/flow,mroch/flow,AgentME/flow,samwgoldman/flow,gabelevi/flow,claudiopro/flow,samwgoldman/flow,jamesgpearce/flow,JonathanUsername/flow,nmote/flow,JonathanUsername/flow,jamesgpearce/flow,AgentME/flow,nmote/flow,samwgoldman/flow,JonathanUsername/flow,claudiopro/flow,popham/flow,facebook/flow,mroch/flow,facebook/flow,jamesgpearce/flow,gabelevi/flow,mroch/flow,AgentME/flow,popham/flow,popham/flow,popham/flow,mroch/flow,gabelevi/flow,nmote/flow,facebook/flow,JonathanUsername/flow,gabelevi/flow,nmote/flow,jamesgpearce/flow,jamesgpearce/flow,mroch/flow,facebook/flow,JonathanUsername/flow,jamesgpearce/flow,jamesgpearce/flow,facebook/flow,nmote/flow,gabelevi/flow,mroch/flow,nmote/flow,claudiopro/flow,AgentME/flow,claudiopro/flow,popham/flow,JonathanUsername/flow,samwgoldman/flow,popham/flow,gabelevi/flow