feat(OIDC): add back channel logout (#8837)

# Which Problems Are Solved

Currently ZITADEL supports RP-initiated logout for clients. Back-channel
logout ensures that user sessions are terminated across all connected
applications, even if the user closes their browser or loses
connectivity providing a more secure alternative for certain use cases.

# How the Problems Are Solved

If the feature is activated and the client used for the authentication
has a back_channel_logout_uri configured, a
`session_logout.back_channel` will be registered. Once a user terminates
their session, a (notification) handler will send a SET (form POST) to
the registered uri containing a logout_token (with the user's ID and
session ID).

- A new feature "back_channel_logout" is added on system and instance
level
- A `back_channel_logout_uri` can be managed on OIDC applications
- Added a `session_logout` aggregate to register and inform about sent
`back_channel` notifications
- Added a `SecurityEventToken` channel and `Form`message type in the
notification handlers
- Added `TriggeredAtOrigin` fields to `HumanSignedOut` and
`TerminateSession` events for notification handling
- Exported various functions and types in the `oidc` package to be able
to reuse for token signing in the back_channel notifier.
- To prevent that current existing session termination events will be
handled, a setup step is added to set the `current_states` for the
`projections.notifications_back_channel_logout` to the current position

- [x] requires https://github.com/zitadel/oidc/pull/671

# Additional Changes

- Updated all OTEL dependencies to v1.29.0, since OIDC already updated
some of them to that version.
- Single Session Termination feature is correctly checked (fixed feature
mapping)

# Additional Context

- closes https://github.com/zitadel/zitadel/issues/8467
- TODO:
  - Documentation
  - UI to be done: https://github.com/zitadel/zitadel/issues/8469

---------

Co-authored-by: Hidde Wieringa <hidde@hiddewieringa.nl>

internal/command/oidc_session.go

@@ -18,6 +18,7 @@ import (
 	"github.com/zitadel/zitadel/internal/id"
 	"github.com/zitadel/zitadel/internal/repository/authrequest"
 	"github.com/zitadel/zitadel/internal/repository/oidcsession"
+	"github.com/zitadel/zitadel/internal/repository/sessionlogout"
 	"github.com/zitadel/zitadel/internal/repository/user"
 	"github.com/zitadel/zitadel/internal/telemetry/tracing"
 	"github.com/zitadel/zitadel/internal/zerrors"
@@ -133,7 +134,8 @@ func (c *Commands) CreateOIDCSessionFromAuthRequest(ctx context.Context, authReq
 func (c *Commands) CreateOIDCSession(ctx context.Context,
 	userID,
 	resourceOwner,
-	clientID string,
+	clientID,
+	backChannelLogoutURI string,
 	scope,
 	audience []string,
 	authMethods []domain.UserAuthMethodType,
@@ -161,6 +163,7 @@ func (c *Commands) CreateOIDCSession(ctx context.Context,
 	}
 
 	cmd.AddSession(ctx, userID, resourceOwner, sessionID, clientID, audience, scope, authMethods, authTime, nonce, preferredLanguage, userAgent)
+	cmd.RegisterLogout(ctx, sessionID, userID, clientID, backChannelLogoutURI)
 	if err = cmd.AddAccessToken(ctx, scope, userID, resourceOwner, reason, actor); err != nil {
 		return nil, err
 	}
@@ -433,6 +436,26 @@ func (c *OIDCSessionEvents) SetAuthRequestFailed(ctx context.Context, authReques
 	c.events = append(c.events, authrequest.NewFailedEvent(ctx, authRequestAggregate, domain.OIDCErrorReasonFromError(err)))
 }
 
+func (c *OIDCSessionEvents) RegisterLogout(ctx context.Context, sessionID, userID, clientID, backChannelLogoutURI string) {
+	// If there's no SSO session (e.g. service accounts) we do not need to register a logout handler.
+	// Also, if the client did not register a backchannel_logout_uri it will not support it (https://openid.net/specs/openid-connect-backchannel-1_0.html#BCRegistration)
+	if sessionID == "" || backChannelLogoutURI == "" {
+		return
+	}
+	if !authz.GetFeatures(ctx).EnableBackChannelLogout {
+		return
+	}
+
+	c.events = append(c.events, sessionlogout.NewBackChannelLogoutRegisteredEvent(
+		ctx,
+		&sessionlogout.NewAggregate(sessionID, authz.GetInstance(ctx).InstanceID()).Aggregate,
+		c.oidcSessionWriteModel.AggregateID,
+		userID,
+		clientID,
+		backChannelLogoutURI,
+	))
+}
+
 func (c *OIDCSessionEvents) AddAccessToken(ctx context.Context, scope []string, userID, resourceOwner string, reason domain.TokenReason, actor *domain.TokenActor) error {
 	accessTokenID, err := c.idGenerator.Next()
 	if err != nil {