Added support for multiple flat buttons, also stubbing

Now the user can designate the primary button to be flat rather than
having to use only the secondary button.  This means that there can be
two flat buttons as well.  Also stubbed out unecessary buttons that
aren't shown on all screens.  Finally a few spacing changes.

Bug: 70638633
Test: Built and flashed
Change-Id: I409c50b4fe579d7cd388b5e0245bafb8becd8e25