Modify OpenRoadmInterfaces implementations

Modify OpenRoadmInterfaces implementations

When we create a new interface on a device, we need to take into account
this new interface just after the mapping update. Unfortunatelly, it
may happen sometimes that the new interface is not present yet in the
operational device datastore at the moment the mapping update occurs.
To avoid such roll-back root cause error, this change modifies the
postInterface method to introduce a check of the new interface presence
before returning. As for the deleteInterface method, it also invokes
the mapping update to remove supporting-interfaces.

JIRA: TRNSPRTPCE-539
Signed-off-by: Gilles Thouenon <gilles.thouenon@orange.com>
Change-Id: I61dfc1021a32626341f69922749bf1f9ba9a1062