Refactor keyboarding code (FWNX-1122)

Replace the keyboarding code with the functionality of FW's
keyboarding library.

This is a preliminary checkin; some tests on Linux may still be failing.
However, it does seem to work (in conjunction with FLEx changes).

Change-Id: Ib102017e41380b4ec95af16c531f48455f2d7073