openid
Add support for request encryption
Resolves Issue #339
The adds in a new credential issuer metadata parameter to support Credential Request encryption.
Merging this with the existing credential response encryption was considered, but given we allow all permutations of mandatory/optional/not supported for both request and response independently, there isn't a great way to do this.
If we required issuers to be consistent on support or not then these would be cleaner as single parameter (but perhaps something we should leave to HAIP).
To be consistent with HAIP, alg is now required in the jwk, a common section on how to perform selection is included and kid must be included if available.
The removal of alg is a breaking change but IMO is worth while to be consistent across the specs.
