`send_wayland_message` takes in the number of words, not its byte size.
This meant that we were sending quite a bit of out-of-bounds stuff
alongside the four arguments required by
`xdg_positioner::set_anchor_rect`, which triggered an assertion on Jay.
This didn't pop up before because the C wayland server library does not
seem to check this, but it's a valid (and useful!) assertion
for other server implementations nonetheless.
This patch switches to the initializer_list syntax to make the intent
clearer.
This patch introduces a new protocol proxy, which multiplxes Wayland
clients into a single connection, allowing us to redirect calls (e.g.
create toplevel -> create subsurface). Mixed with some state tracking
and emulation, we can embed a full-featured client into the editor.
