Another day, another wayland refactor. Way back when, dcc3c2e added
support for the hidpi-window-scale option (something you probably should
never set to no but whatever) to wayland. Well technically, it never had
any runtime toggling support (don't remember if detecting when vo_opts
changed was possible or not then; maybe not). Anyways in the process of
fixing that, I went ahead and refactored how this is all handled. The
key difference is that when hidpi-window-scale is disabled, wl->scaling
is directly set to 1 instead of forcibly setting
wl->current_output->scale to 1. Note that scaling operations don't
always require a geometry reset/resize so set_surface_scaling needs to
be separate from set_geometry. The logic here is kind of complicated but
it (should) be correct.