ui: added find shortcut to set focus in search view

The shortcut is added to the new Find menubar item and dispatches a MessageFind, which is handled by the
SearchController. QtSearchView assures via the ViewLayout that the view is visible when setting focus on the search box.

src/lib/component/controller/SearchController.cpp

@@ -33,6 +33,11 @@ void SearchController::handleMessage(MessageActivateToken* message)
 	getView()->setText(m_graphAccess->getNameForNodeWithId(message->tokenId));
 }
 
+void SearchController::handleMessage(MessageFind* message)
+{
+	getView()->setFocus();
+}
+
 void SearchController::handleMessage(MessageFinishedParsing* message)
 {
 	getView()->setAutocompletionList(m_graphAccess->getNamesForNodesWithNamePrefix(""));