Add SCIM schema

[marcvs]

Translate eduperson definitions to SCIM.

[surfnet-niels]

This work was posted in a subdirectory "SCIM".
The example file is I think SCIM specific, however, the schema file, does not have any SCIM specific elements?
As such I woud suggest to move the schema file to a hight level, while the SCIM example should probably stay in a SCIM subdir

[surfnet-niels]

One thing that needs discussion here is names of the attributes/claims:
This schema is using e.g. "eduPersonAffiliation" (which minics the eduPerson etc schema directly), whereas OIDC related usage would suggest claims named like "eduperson_scoped_affiliation", as per https://wiki.refeds.org/display/CON/Consultation%3A+SAML2+and+OIDC+Mappings?preview=/38895621/38895643/20181011-OIDC-WP.pdf
How do we deal with this for SCIM?
(note that in the VC space as all protocols are OIDC-ish anyway using claims is obvious)

[marcvs]

While I prefer the under_scores (as in OIDC), the SCIM core schema uses CamelCase itself.
I think we should to stick to CamelCase for SCIM, and use the mapping of the (still draft but well-used) OIDCRE Whitepaper [1] (lines 192ff) to map to under_score syntax.

[1] https://docs.google.com/document/d/1b-Mlet3Lq7qKLEf1BnHJ4nL1fq-vMe7fzpXyrq2wp08

[simmel]

I agree with sticking to CamelCase. This is a leaky "abstraction" for a good reason.