Usage of event-basedOn extension instead of redefining CompositionBasedOnOrderOrRequisition

[nriss]

It would be better to use the event-basedOn extension (maybe by adding constraints on reference type and the context)

Definition of extension in HL7-eu :

extensions/input/fsh/extensions/extensions-lab.fsh

Line 2 in ea71ac4

Extension: CompositionBasedOnOrderOrRequisition

Definition of the global extension :

https://hl7.org/fhir/extensions/5.2.0/StructureDefinition-event-basedOn.html

Issue identified with @souadbenmustapha

Linked issue - https://github.com/hl7-eu/imaging/issues/86