feat: VoBasedEdupersonScopedAffiliationsClaimSource impl

Implementation of a claim source to generate EPSA values based on vo
membership. ClaimSource requires congiruation option 'valueMap', in the
format of 'voId:aff,aff|voId:aff,aff'. If the user is a valid member of
a VO with id 'voId', all affiliation values are added into the claim
value.