This merge request adds a new appmenu protocol, allowing clients to notify compositors about the DBus object path and service name of their application menu implementing the
com.canonical.dbusmenu interface. This allows a compositor to render application menus using its own UI or forwarding this information to a client dedicated to rendering application menus.
This protocol is based off of the
org_kde_kwin_appmenu protocol implemented by KDE's KWin compositor and
plasma-integration for Qt clients.