This commit will combine the code of ListItemAdapter &
  GridItemAdapter in LibreOfficeUIActivity to one
  ExplorerItemAdapter which will handle both the view
  types.

Change-Id: I45c1f5124afee82ff0b78f13609acd37be87fde1
Reviewed-on: https://gerrit.libreoffice.org/34680Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Aleksandar Stefanović <theonewithideas@gmail.com>
Tested-by: Aleksandar Stefanović <theonewithideas@gmail.com>