OpenID: Expose user info claims in Identity.

[mickeykcyolo]

Is your feature request related to a problem?

No.

Describe the solution you'd like to see

It would be really awesome and benefit all to add the claims data as []byte or string to connector.Identity.
This would enable developers the ability to scan the claims freely using JSONPath for example,
thus developers won't have to stick only to the basic exposed user attributes.

Describe alternatives you've considered

The only alternative I found is using the refresh token to get a new access/id token and then searching the id token for any custom attribute or making another request to user info.
This alternative is really bad as it is enforcing the client to enable the refresh token and enforcing us to use internal OpenID code outside of DEX.

Additional context

It could be relevant to SAML also. In this case the claims would be the SAML response xml as []byte or string.

Thanks for your great work on DEX,
Mickey

[candlerb]

PR #1841, which is an implementation of middleware (#1635), adds CustomClaims to the connector.Identity struct as a map[string]interface{}