Change voice room callsign format to "callsign (userid)"

So far the callsign, was the callsign itself only. However, other VATSIM
clients expect it to include the user id in brackets.

ref T354

src/blackcore/voicechannel.h

@@ -58,6 +58,9 @@ namespace BlackCore
         //! Set own aircraft's callsign
         virtual void setOwnAircraftCallsign(const BlackMisc::Aviation::CCallsign &callsign) = 0;
 
+        //! Set user id
+        virtual void setUserId(const QString &id) = 0;
+
         //! Get voice room
         virtual BlackMisc::Audio::CVoiceRoom getVoiceRoom() const = 0;