refactor: use struct types for claim related types (#283)

* oidc: add regression tests for token claim json

this helps to verify that the same JSON is produced,
after these types are refactored.

* refactor: use struct types for claim related types

BREAKING CHANGE:
The following types are changed from interface to struct type:

- AccessTokenClaims
- IDTokenClaims
- IntrospectionResponse
- UserInfo and related types.

The following methods of OPStorage now take a pointer to a struct type,
instead of an interface:

- SetUserinfoFromScopes
- SetUserinfoFromToken
- SetIntrospectionFromToken

The following functions are now generic, so that type-safe extension
of Claims is now possible:

- op.VerifyIDTokenHint
- op.VerifyAccessToken
- rp.VerifyTokens
- rp.VerifyIDToken

- Changed UserInfoAddress to pointer in UserInfo and
IntrospectionResponse.
This was needed to make omitempty work correctly.
- Copy or merge maps in IntrospectionResponse and SetUserInfo

* op: add example for VerifyAccessToken

* fix: rp: wrong assignment in WithIssuedAtMaxAge

WithIssuedAtMaxAge assigned its value to v.maxAge, which was wrong.
This change fixes that by assiging the duration to v.maxAgeIAT.

* rp: add VerifyTokens example

* oidc: add standard references to:

- IDTokenClaims
- IntrospectionResponse
- UserInfo

* only count coverage for `./pkg/...`

pkg/op/token_exchange.go

@@ -280,9 +280,9 @@ func GetTokenIDAndSubjectFromToken(
 ) (tokenIDOrToken, subject string, claims map[string]interface{}, ok bool) {
 	switch tokenType {
 	case oidc.AccessTokenType:
-		var accessTokenClaims oidc.AccessTokenClaims
+		var accessTokenClaims *oidc.AccessTokenClaims
 		tokenIDOrToken, subject, accessTokenClaims, ok = getTokenIDAndClaims(ctx, exchanger, token)
-		claims = accessTokenClaims.GetClaims()
+		claims = accessTokenClaims.Claims
 	case oidc.RefreshTokenType:
 		refreshTokenRequest, err := exchanger.Storage().TokenRequestByRefreshToken(ctx, token)
 		if err != nil {
@@ -291,12 +291,12 @@ func GetTokenIDAndSubjectFromToken(
 
 		tokenIDOrToken, subject, ok = token, refreshTokenRequest.GetSubject(), true
 	case oidc.IDTokenType:
-		idTokenClaims, err := VerifyIDTokenHint(ctx, token, exchanger.IDTokenHintVerifier(ctx))
+		idTokenClaims, err := VerifyIDTokenHint[*oidc.IDTokenClaims](ctx, token, exchanger.IDTokenHintVerifier(ctx))
 		if err != nil {
 			break
 		}
 
-		tokenIDOrToken, subject, claims, ok = token, idTokenClaims.GetSubject(), idTokenClaims.GetClaims(), true
+		tokenIDOrToken, subject, claims, ok = token, idTokenClaims.Subject, idTokenClaims.Claims, true
 	}
 
 	if !ok {
@@ -380,7 +380,7 @@ func CreateTokenExchangeResponse(
 	}, nil
 }
 
-func getTokenIDAndClaims(ctx context.Context, userinfoProvider UserinfoProvider, accessToken string) (string, string, oidc.AccessTokenClaims, bool) {
+func getTokenIDAndClaims(ctx context.Context, userinfoProvider UserinfoProvider, accessToken string) (string, string, *oidc.AccessTokenClaims, bool) {
 	tokenIDSubject, err := userinfoProvider.Crypto().Decrypt(accessToken)
 	if err == nil {
 		splitToken := strings.Split(tokenIDSubject, ":")
@@ -390,10 +390,10 @@ func getTokenIDAndClaims(ctx context.Context, userinfoProvider UserinfoProvider,
 
 		return splitToken[0], splitToken[1], nil, true
 	}
-	accessTokenClaims, err := VerifyAccessToken(ctx, accessToken, userinfoProvider.AccessTokenVerifier(ctx))
+	accessTokenClaims, err := VerifyAccessToken[*oidc.AccessTokenClaims](ctx, accessToken, userinfoProvider.AccessTokenVerifier(ctx))
 	if err != nil {
 		return "", "", nil, false
 	}
 
-	return accessTokenClaims.GetTokenID(), accessTokenClaims.GetSubject(), accessTokenClaims, true
+	return accessTokenClaims.JWTID, accessTokenClaims.Subject, accessTokenClaims, true
 }