This new component contains several overlays and dialogs, and is
intended to manage interactions with a change edit. The previously
created component, gr-edit-file-controls, is a dumb component that just
fires events corresponding to the button array it contains -- this
component will have public functions callable with a path that open
dialogs allowing users to do things like delete, revert, and open files
in a change edit.
Bug: Issue 4437
Change-Id: I83ed7319f82d65bccea68554a620555182f117bf