This should fix an issue where output hotplug can sometimes cause
clients (including XWayland) to crash with a protocol error trying to
bind the output.
Using a timer doesn't seem ideal, but seems to be the correct way to do
this at present. Wlroots `wlr_global_destroy_safe` is basically the same
as this.
Adding a `LoopHandle` argument to `OutputConfigurationState::new` seems
awkward, but maybe better than a handler method for removing globals.
(`IdleNotifierState::new` also takes a `LoopHandle`). Perhaps Smithay
could provide some kind of helper for this.
`Output` in Smithay doesn't track if the output still exists, other than
based on whether or not it has strong references. Which doesn't seem to
be working correctly.
There may be leaked strong references to `Output`s somewhere, and maybe
Smithay should track if an output is still valid, generally when it is
exposed as a Wayland global
(https://github.com/Smithay/smithay/issues/1584). But a check like this
works for now.
Addresses https://github.com/pop-os/cosmic-comp/issues/985.
