Issue #2781577 by tim.plunkett, tkoleary, Bojhan, rickvug, Wim Leers: Properly style outside-in off canvas tray

Issue #2753941 by tedbow, tim.plunkett, tkoleary, SKAUGHT, drpal, effulgentsia, andrewmacpherson, webchick, xjm, Bojhan, Gábor Hojtsy, Wim Leers, catch, nod_: [Experimental] Create Outside In module MVP to provide block configuration in Off-Canvas tray and expand site edit mode