[Federation] multiple entity_type at the listing endpoint

[Giuseppe De Marco]

In the listing endpoint we may require to filter the entities providing multiple entity types, like:

entity_type=intermediate

and

entity_type=openid_relying_party

where multiple ulrparams forms an array, exactly like resource indicators (RFC 8707), like:

entity_type=openid_provider&entity_type=relying_party

‌

[Giuseppe De Marco]

provided PR, here
https://bitbucket.org/openid/connect/pull-requests/696

[Giuseppe De Marco]

Resolved by https://bitbucket.org/openid/connect/pull-requests/696