[hack] Implement naming for darray and varray
[hack] Implement naming for darray and varray

Summary:
Carries `darray` and `varray` through naming. This involves naming `darray` and `varray` when used as an expression, and naming `darray` and `varray` when used as a type annotation.

This diff intentionally does not introduce new typing semantics. `darray` and `varray` are translated into `array` for typing purposes. A subsequent diff will update `typing_defs.ml` and `typing.ml` to introduce typing versions of these constructs.

Reviewed By: eshrews

Differential Revision: D4689889

fbshipit-source-id: 135dd44b7152c2ab9d7e97bf51f8beb8ec443340

facebook/flow,gabro/flow,MichaelDeBoey/flow,AgentME/flow,gabelevi/flow,facebook/flow,gabelevi/flow,AgentME/flow,samwgoldman/flow,gabro/flow,claudiopro/flow,facebook/flow,TiddoLangerak/flow,popham/flow,jamesgpearce/flow,facebook/flow,TiddoLangerak/flow,ylu1317/flow,popham/flow,AgentME/flow,jamesgpearce/flow,facebook/flow,JonathanUsername/flow,nmote/flow,JonathanUsername/flow,MichaelDeBoey/flow,fletcherw/flow,nmote/flow,jamesgpearce/flow,jamesgpearce/flow,claudiopro/flow,samwgoldman/flow,JonathanUsername/flow,JonathanUsername/flow,fletcherw/flow,MichaelDeBoey/flow,popham/flow,MichaelDeBoey/flow,ylu1317/flow,jamesgpearce/flow,JonathanUsername/flow,nmote/flow,fletcherw/flow,facebook/flow,gabro/flow,gabro/flow,gabelevi/flow,popham/flow,fletcherw/flow,TiddoLangerak/flow,nmote/flow,popham/flow,claudiopro/flow,gabro/flow,nmote/flow,ylu1317/flow,jamesgpearce/flow,mroch/flow,gabelevi/flow,TiddoLangerak/flow,mroch/flow,AgentME/flow,mroch/flow,mroch/flow,fletcherw/flow,gabelevi/flow,claudiopro/flow,nmote/flow,AgentME/flow,JonathanUsername/flow,claudiopro/flow,jamesgpearce/flow,samwgoldman/flow,ylu1317/flow,ylu1317/flow,TiddoLangerak/flow,JonathanUsername/flow,facebook/flow,fletcherw/flow,samwgoldman/flow,mroch/flow,popham/flow,gabelevi/flow,MichaelDeBoey/flow,samwgoldman/flow,samwgoldman/flow,gabelevi/flow,mroch/flow,nmote/flow,mroch/flow,popham/flow,samwgoldman/flow,gabro/flow