Support unregistered Qt namespace enums in QML methods.

Support unregistered Qt namespace enums in QML methods.

This brings the support in line with signal handlers, which should allow
us to reuse the implementation there when appropriate. Also adds tests
for both registered and unregisted Qt namespace enums.

Change-Id: I366846626fc44d6d99b51e93fc9e3cb948c748f9
Reviewed-by: Chris Adams <christopher.adams@nokia.com>