The dock widget's togglViewActions text is tied to the widget title,
but the view headers should not display a potential "&" accelerator.

So stash the &'d string away when setting up the title and retrieve
it when re-creating the view menu.

Task-number: QTCREATORBUG-19378
Change-Id: I6bf49ca526d12ddd57dfa33a94327a83baeaa6b4
Reviewed-by: Eike Ziller <eike.ziller@qt.io>