Make AppWidgets encryption-aware.

Only parse and load AppWidget configuration details after a user has
been unlocked.  Yell loudly if someone accidentally tries loading
data for a locked user.

Tidy up protected broadcast logic a bit more to handle persistent
processes.  Add backwards compatible behavior for APPWIDGET_UPDATE
broadcast simliar to APPWIDGET_CONFIGURE, since some apps are sending
it to themselves.

Add hidden USER_HANDLE extra to a handful of broadcasts to make
logic more consistent.

Bug: 26247049, 26219971
Change-Id: I54e4f2e343488571f9baa1a316962f41186c1a2c