WIP towards revoking upstream refresh tokens during GC

- Discover the revocation endpoint of the upstream provider in
  oidc_upstream_watcher.go and save it into the cache for future use
  by the garbage collector controller
- Adds RevokeRefreshToken to UpstreamOIDCIdentityProviderI
- Implements the production version of RevokeRefreshToken
- Implements test doubles for RevokeRefreshToken for future use in
  garbage collector's unit tests
- Prefactors the crud and session storage types for future use in the
  garbage collector controller
- See remaining TODOs in garbage_collector.go

internal/fositestorage/authorizationcode/authorizationcode.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/ory/fosite"
 	"github.com/ory/fosite/handler/oauth2"
+	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/errors"
 	corev1client "k8s.io/client-go/kubernetes/typed/core/v1"
 
@@ -48,6 +49,23 @@ func New(secrets corev1client.SecretInterface, clock func() time.Time, sessionSt
 	return &authorizeCodeStorage{storage: crud.New(TypeLabelValue, secrets, clock, sessionStorageLifetime)}
 }
 
+// ReadFromSecret reads the contents of a Secret as an AuthorizeCodeSession.
+func ReadFromSecret(secret *v1.Secret) (*AuthorizeCodeSession, error) {
+	session := NewValidEmptyAuthorizeCodeSession()
+	err := crud.FromSecret(TypeLabelValue, secret, session)
+	if err != nil {
+		return nil, err
+	}
+	if session.Version != authorizeCodeStorageVersion {
+		return nil, fmt.Errorf("%w: authorization code session has version %s instead of %s",
+			ErrInvalidAuthorizeRequestVersion, session.Version, authorizeCodeStorageVersion)
+	}
+	if session.Request.ID == "" {
+		return nil, fmt.Errorf("malformed authorization code session: %w", ErrInvalidAuthorizeRequestData)
+	}
+	return session, nil
+}
+
 func (a *authorizeCodeStorage) CreateAuthorizeCodeSession(ctx context.Context, signature string, requester fosite.Requester) error {
 	// This conversion assumes that we do not wrap the default type in any way
 	// i.e. we use the default fosite.OAuth2Provider.NewAuthorizeRequest implementation