FEAT(server): Remove DBus support

The DBus RPC interface on the server has been deprecated for a while and
has also not been maintained for even longer. Therefore, the API has now
been removed completely.

Instead, users shall make use of the ZeroC Ice interface as a means to
do RPC.

Fixes mumble-voip#6548

auxiliary_files/mumble-server.ini

@@ -48,15 +48,6 @@ database=
 ;dbPrefix=mumble-server_
 ;dbOpts=
 
-;  The server defaults to not using D-Bus. If you wish to use dbus, which is one of the
-; RPC methods available in the server, please specify so here.
-;
-;dbus=session
-
-; Alternate D-Bus service name. Only use if you are running distinct
-; mumble server processes connected to the same D-Bus daemon.
-;dbusservice=net.sourceforge.mumble.murmur
-
 ; If you want to use ZeroC Ice to communicate with the server, you need
 ; to specify the endpoint to use. Since there is no authentication
 ; with ICE, you should only use it if you trust all the users who have

src/murmur/CMakeLists.txt

@@ -183,19 +183,6 @@ if(zeroconf)
 	)
 endif()
 
-if(NOT WIN32 AND NOT APPLE)
-	find_pkg(Qt6 COMPONENTS DBus REQUIRED)
-
-	target_sources(mumble-server
-		PRIVATE
-			"DBus.cpp"
-			"DBus.h"
-	)
-
-	target_compile_definitions(mumble-server PUBLIC "USE_DBUS")
-	target_link_libraries(mumble-server PRIVATE Qt6::DBus)
-endif()
-
 if(ice)
 	find_pkg(Ice
 		COMPONENTS