CDefView: Make GetItemObject return an IContectMenu after setting itself as the site.
CDefViewBckgrndMenu: Make the inner context menu use the same site. Implement handling CMDSTR_VIEWLISTA and CMDSTR_VIEWDETAILSA.
CDefaultContextMenu: CMDSTR_VIEWLISTA and CMDSTR_VIEWDETAILSA shouldn't be handled in this class.
Fixes CORE-14327 and the two buttons that change the view mode
It shouldn't be necessary for QueryContextMenu to be called before InvokeCommand.
Move retrieving the IContextMenu of the folder to the initialization of the class.
CORE-12866
