conform id token end-user claims feature toggle

[panva]

Core 1.0 - 5.4. Requesting Claims using Scope Values defines that claims requested using the scope parameter are returned from the UserInfo Endpoint
unless the response_type=id_token.

The Claims requested by the profile, email, address, and phone scope values are returned from the
UserInfo Endpoint, as described in Section 5.3.2, when a response_type value is used that results
in an Access Token being issued. However, when no Access Token is issued (which is the case for
the response_type value id_token), the resulting Claims are returned in the ID Token.

To enable/disable this conform behaviour

const configuration = { features: { conformIdTokenClaims: Boolean[false] } };

The conform/non-conform behaviour results in the following results

flag value	request params	authorization_endpoint ID Token (if issued)	token_endpoint ID Token (if issued)
false	response_type= any scope=openid email	✅ sub ✅ email ✅ email_verified	✅ sub ✅ email ✅ email_verified
true	response_type= any but id_token scope=openid email	✅ sub ❌ email ❌ email_verified	✅ sub ❌ email ❌ email_verified
true	response_type= any but id_token scope=openid email claims={"id_token":{"email":null}}	✅ sub ✅ email ❌ email_verified	✅ sub ✅ email ❌ email_verified
true	response_type=id_token scope=openid email	✅ sub ✅ email ✅ email_verified	n/a

[codecov]

Codecov Report

Merging #298 into master will not change coverage.
The diff coverage is 100%.

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