shell: Remove SHELL_SURFACE_FULLSCREEN and SHELL_SURFACE_MAXIMIZED.
shell: Remove SHELL_SURFACE_FULLSCREEN and SHELL_SURFACE_MAXIMIZED.

These surface types don't exist anymore inside weston desktop shell
implementation. They are just exposed as wl_shell surface types, but
internally the implementation is done with surface states.

The previous behavior (setting a surface type unsets another one) still
happens when using wl_shell. This change is mainly done as a refactory
to allow xdg-shell to use the same code.

giucam/weston,Tarnyko/weston-xdg_surface_present,kwm81/weston,jonnylamb/weston,Gnurou/weston,giucam/weston,sir-murray/weston,krezovic/weston,Gnurou/weston,udoprog/weston,eyolfson/weston,Tarnyko/weston-xdg_surface_present,Fantu/compositor-spice,xorgy/weston,kwm81/weston,jonnylamb/weston,mchalupa/weston,mchalupa/weston,Fantu/compositor-spice,krezovic/weston,udoprog/weston,Fantu/compositor-spice,xorgy/weston,eyolfson/weston,sir-murray/weston