toplevel-info/mgmt: various updates

[Drakulix]

cc @ids1024 @wash2

This bases zcosmic_toplevel_info_unstable_v1 on ext_foreign_toplevel_list_v1, by adding a new get_cosmic_toplevel request and deprecating all events/requests replaced by existing ext_foreign_toplevel_list_v1 events/requests.

It also adds a global done-event meant to aid tracking e.g. focus changes for pop-os/cosmic-launcher#150.

Lastly it adds our new sticky window state for both zcosmic_toplevel_info_unstable_v1 and zcosmic_toplevel_management_unstable_v1. I don't think we have a concrete use-case for this, but I figured it wouldn't hurt.

[ids1024]

This seems good, and matches what I was imagining if we want to avoid a breaking protocol update (which I guess would only allow cleaning up the deprecated events; and not having to implement the older version in the compositor).

We can update cctk to handle this protocol together with ext-foreign-toplevel-list-v1 (similarly to how sctk handles wl_output/xdg_output). Maybe with just a hard dependency on the new version of the protocol, as long as we're careful to land this in the compositor before making use of it elsewhere.