Add store Metadata class to redex python scripts to output dex metadata
Add store Metadata class to redex python scripts to output dex metadata

Summary:
refactoring to a class for writing out the expected metadata format
Depends on D3729476

Reviewed By: bertmaher

Differential Revision: D3729628

fbshipit-source-id: da95c8804fe2398f40093ea35d8a35fb26dd1ed7

facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex,facebook/redex