[470297] Adapt service according to Sirius changes for labelFormat

According to changes of bug 470297 (following bug 424422), the services
must now return the Enumerator and not an EEnumLiteral.
The Sirius documentation has also been completed for this case.

Bug: 470297
Change-Id: Iaed662a88c8f430b5f012cf5e55dd39eb45c2a8c
Signed-off-by: Laurent Redor <laurent.redor@obeo.fr>
1 file changed