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

pkg/op/auth_request.go

@@ -371,7 +371,7 @@ func ValidateAuthReqIDTokenHint(ctx context.Context, idTokenHint string, verifie
 	if idTokenHint == "" {
 		return "", nil
 	}
-	claims, err := VerifyIDTokenHint(ctx, idTokenHint, verifier)
+	claims, err := VerifyIDTokenHint[*oidc.TokenClaims](ctx, idTokenHint, verifier)
 	if err != nil {
 		return "", oidc.ErrLoginRequired().WithDescription("The id_token_hint is invalid. " +
 			"If you have any questions, you may contact the administrator of the application.")