Add dbus profile() to return profile name of current session

Instead of relying on env variable KONSOLE_PROFILE_NAME, which is
invalid upon switching profiles, use a dbus method profile().

qdbus $KONSOLE_DBUS_SERVICE $KONSOLE_DBUS_SESSION profile

CCBUG:406955

src/Session.cpp

@@ -1594,6 +1594,10 @@ int Session::historySize() const
     }
 }
 
+QString Session::profile()
+{
+    return SessionManager::instance()->sessionProfile(this)->name();
+}
 
 void Session::setProfile(const QString &profileName)
 {

src/Session.h

@@ -593,6 +593,11 @@ public Q_SLOTS:
      */
     Q_SCRIPTABLE void setProfile(const QString &profileName);
 
+    /**
+     * Returns the current session's profile name
+     */
+    Q_SCRIPTABLE QString profile();
+
 Q_SIGNALS:
 
     /** Emitted when the terminal process starts. */