Handle LocalKeyboard and GetWsForCulture

Add WritingSystemDefinition.LocalKeyboard. Clean up various related
things to support various default behaviors.

Add WritingSystemRepository.LocalKeyboardSettings to get and set
the data that should be persisted somewhere local.

Add WritingSystemRepository.GetWsForInputLanguage to handle
InputLangChanged.

Also extends implementation of Clone() and Equals() to the new
properties.  I don't know whether anything actually requires these
properties to be cloned and considered for equality, but it seemed
safest to handle them. I think Clone, at least, is used when
a temporary WS in the FW writing system dialog is copied to a real store.

Change-Id: Ifef99ab28cb9d1087f5388acd3a46dfde6228e18