Direct keyman support

Re-adds support for direct Keyman keyboard support which was removed with the recent keyboard handling changes.
Also added backwards compatibility for keyboard IDs from older versions of Palaso and Paratext.
I'm trying to remember from 7 months ago, but I think that it's because WinKeyboardAdaptor is an internal class and ActivateDefaultKeyboard is not part of the IKeyboardAdaptor interface so there is no way it was used so we just removed it.