[Openid-specs-ab] Issue #1446: Listing by type (openid/connect)

[peppelinux]

New issue 1446: Listing by type
https://bitbucket.org/openid/connect/issues/1446/listing-by-type

Giuseppe De Marco:

Working on the concrete implementation of OIDC Federation I realized that it would be useful for a Relying Party to use the List response to get the list of POs for which build the trust chain and also the discovery page, where the user selects where to authenticate.

For this reason I propose to add the following to the List endpoint request parameters:  
  
**type**

OPTIONAL. A specific entity type to filter. If no value is given then all metadata types are expected to be returned.