librbd/image: mask out all implicit features when creating an image

librbd/image: mask out all implicit features when creating an image

This will ensure that all paths to the create image state machine
properly handle this condition. Previously, it was up to the callers
of the state machine to clear the implicit feature bits.

Fixes: https://tracker.ceph.com/issues/48647
Signed-off-by: Jason Dillaman <dillaman@redhat.com>