Add fullscreen protocol

Map the surface as a fullscreen surface. On the output the
surface is assigned to. The client can use different fulllscreen
method to fix the size mismatch issue: default, scale, driver
and fill.

Hints to indicate compositor how to deal with this fullscreen surface.

"default" means the client has no preference on fullscreen
          behavior, policies are determined by compositor.
"scale"   means the client prefers scaling by the compositor.
          Scaling would always preserve surface's aspect ratio.
          And the surface is centered.
"driver"  means the client wants to switch video mode to the
          smallest mode that can fit the client buffer. If the
          sizes do not match, black borders are added. And the
          framerate parameter is used for "driver" method,
          to indicate the preferred framerate. framerate=0 means
          that the app does not care about framerate
"fill"    means the client wants to add blackborders to the
          surface. This would be preferring 1:1 pixel mapping
          in the monitor native video mode. The surface is
          centered.