When authenticating with OIDC, allow per-OP configuration of desired scopes. #275
Description
Different OPs support different scopes.
Currently, dCacheView uses a hard-coded list of scopes to request when initiating implicit flow: openid profile email.
Some OPs use the eduperson_entitlement claim to describe group-membership. The presence of the eduperson_entitlement claim is controlled by the eduperson_entitlement scope. Therefore, in order for dCache to learn group-membership, dCacheView should (also) request the eduperson_entitlement scope.
However, not all OPs support the eduperson_entitlement scope and requesting a non-existing scope can cause the login to fail.
Therefore, it is important to allow per-OP configuration of the desired scopes.