Candidate properties in MOD for "direct" inclusion in the metadata model

[jonquet]

There are multiples metadata properties in MOD (since 1.4) that are not directly available in the AgroPortal metadata model because they were already available and implemented "differently" in the original BioPortal metadata model.
(in fact these properties influenced MOD and are often the reason why there are in MOD now)

With the first iteration of work on metadata in 2017, we decided not to include them as a repetition in the Submission object.

Now, in order to anticipate the capacity to return metadata following several "profiles" we coud consider adding them.
Mostly this concerns the properties for which the range is another complex object in the model. Listed hereafter:

• Access rights@en ; droits d'accès@fr [bpm:viewingRestriction]
• Group@en ; Groupe@fr [bpm:group]
• Used in project@en ; utilisé dans le projet@fr [bpm:projects]
• Is part of (view of)@en ; est partie (une vue) de@fr [bpm:viewOf]
• Root resources@en ; ressource racine@fr [bpm:roots]
• Classes partition@en ; partition des classes@fr [bpm:classes]
• Properties partition@en ; partition des propriétés@fr [bpm:properties]
• Has version @en ; a pour version@fr [bpm:submissions]
• Changes@en ; changements@fr [bpm:diffFilePath]

We need to see if we can add "equivalences" for them in the model (as we do for the other added properties) AND if it will be easy to "serialize" the object in our model into the form expected by the object in the range in the property in profile used to return the metadata.

[syphax-bouazzouni]

related to #103