zink: use imageless framebuffers

zink: use imageless framebuffers

this feature lets zink avoid the screen-based framebuffer cache with locks
in favor of a context-based one that doesn't need any complicated wizardry
to work since it doesn't need to track refcounts for attachments or work
across contexts since the surface info gets passed in when the renderpass
is begun

also expand the dummy surface to an array for use with multisampling and simplify
surface refs there for non-imageless case

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12661>