rp-adapter: client registration

[llorllale]

The RP Adapter currently implements a custom client registration endpoint:

Example

Request:

HTTP POST

{
    "label": "Acme University",
    "callback":"http://example.acme.edu/oauth2/callback",
    "scopes": ["openid", "book", "newspaper"]
}

Response:

HTTP 201 CREATED

{
    "clientID": "75095612-d5c4-44ee-a824-6ec50578b825",
    "clientSecret": "rGDy~Fwf8Hocym8y1q5~da5IV9",
    "publicDID": "did:trustbloc:testnet.trustbloc.local:EiAZRRfUgI9qnsUdYyL9dY40I5JOOJjQURgXFQ5HzYjGeQ"
}

We should attempt to conform to existing standards and rationalize any deviations from them:

• OAuth 2.0 Dynamic Client Registration Protocol
• OpenID Connect Dynamic Client Registration 1.0