implement kde appmenu protocol

[ilsubyeega]

• Implement smithay and handler.
• Refactor smithay implementation; i believe this is not ideal implementation and could be more cleaner. (hope yalter can fix this)
• Figure out where to save the state of client
• FIXME: make this protocol OPT-IN since most of client will hide the menu when this protocol exists in the session

Notes:

• used just raw xml protocol specifications but wayland-protocol-plasma exists by smithay, but not reexported
• compositor only need to save the 2 data(service_name and object_path) and then export somewhere, maybe realtime, if i understood correctly.
• for dbusmenu implementation just wip stuffs are here: https://github.com/ilsubyeega/appmenu

The appmenu works with (ignoring xwayland support):

• wayland compositor with appmenu protocol support
• client that supports kde appmenu wayland protocol; when they do, they register new d-bus bus which contains /MenuBar/..., and then sends org_kde_kwin_appmenu#send_address(service_name, object_path) to compositor
• the application(shell) to listen the active/focused window and its service_name/object_path. probably niri ipc could do that

DO NOT MERGE YET: todo!() will panic your environment

[HigherOrderLogic]

I dont think Yalter is going to accept this PR but anyway...

[Sempyos]

Can you explain why we need to implement this protocol..?

[ilsubyeega]

Can you explain why we need to implement this protocol..?

@Sempyos In wayland area, there is no other way to support this feature at this time. See this 6-year old issue: Alexays/Waybar#288