docker: set `DBUS_SESSION_BUS_ADDRESS` so that it uses remote TCP with local fallback: When connecting to Docker service, first the `backend` container will be tried with TCP, then an Unix Socket will be used as fallback. The Unix Socket is put in Libervia local dir which is a volume shared between containers. This way D-Bus can be used with a remote backend, or the backend can be run locally (notably during build when accounts creation or other settings must be done via Libervia CLI).

[Desktop Entry]
Type=Application
Name=Libervia TUI (Primitivus)
Comment=console frontend for Libervia (XMPP)
Exec=libervia-tui
Icon=org.libervia.LiberviaTUI
Categories=Network;InstantMessaging;Chat;FileTransfer;RemoteAccess;
Keywords=xmpp;chat;messaging;im;file;sharing;communication;jabber;social;network;decentralization;console;