Add a generic Drawer view and CtaDrawer

This standardizes the drawer we use for CTAs and will be used in the
upcoming photo upload CTA commit (Story 343). In future, references could also use a subclass of Drawer (as of now, only the styling is shared).

Change-Id: Ice52cf3b288b0f551acd25edc3ec5727c04daf4b
Merge "Add a generic Drawer view and CtaDrawer"