Improve keyboard switching on Windows (LT-15092)

- correctly get names of IMEs through TSF (thanks to Marc Durdin for
  some sample code)
- use TSF for keyboard switching if available
- now supports multiple keyboards per language

Change-Id: I19f44293c44ba52c8b478a9cad262af7bb66801a
Merge "Improve keyboard switching on Windows (LT-15092)" into fw/KeyboardingV2