[MWF] Use Ctrl+PageUp/PageDown for Tab Navigation

In the Windows implementation of the TabControl, Ctrl+PageUp
navigates to the previous tab and Ctrl+PageDown navigates to the
next tab (with both wrapping around).  This change implements this
feature in the Mono implementation.

Change-Id: Ib940bd08d5ba641f05ed91c0e789e356e68f72bb