refactor: clean up some MainWindow stuff

this makes the accounts button and menubar item share the same QMenu
and also refactors some code

Signed-off-by: leo78913 <leo3758@riseup.net>

launcher/ui/MainWindow.h

@@ -239,10 +239,8 @@ private:
     QToolButton *newsLabel = nullptr;
     QLabel *m_statusLeft = nullptr;
     QLabel *m_statusCenter = nullptr;
-    QMenu *accountMenu = nullptr;
     LabeledToolButton *changeIconButton = nullptr;
     LabeledToolButton *renameButton = nullptr;
-    QToolButton *accountMenuButton = nullptr;
     QToolButton *helpMenuButton = nullptr;
     KonamiCode * secretEventFilter = nullptr;