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/repository/user/human.go

@@ -517,7 +517,9 @@ func NewHumanInviteCheckFailedEvent(ctx context.Context, aggregate *eventstore.A
 type HumanSignedOutEvent struct {
 	eventstore.BaseEvent `json:"-"`
 
-	UserAgentID string `json:"userAgentID"`
+	UserAgentID       string `json:"userAgentID"`
+	SessionID         string `json:"sessionID,omitempty"`
+	TriggeredAtOrigin string `json:"triggerOrigin,omitempty"`
 }
 
 func (e *HumanSignedOutEvent) Payload() interface{} {
@@ -528,10 +530,15 @@ func (e *HumanSignedOutEvent) UniqueConstraints() []*eventstore.UniqueConstraint
 	return nil
 }
 
+func (e *HumanSignedOutEvent) TriggerOrigin() string {
+	return e.TriggeredAtOrigin
+}
+
 func NewHumanSignedOutEvent(
 	ctx context.Context,
 	aggregate *eventstore.Aggregate,
-	userAgentID string,
+	userAgentID,
+	sessionID string,
 ) *HumanSignedOutEvent {
 	return &HumanSignedOutEvent{
 		BaseEvent: *eventstore.NewBaseEventForPush(
@@ -539,7 +546,9 @@ func NewHumanSignedOutEvent(
 			aggregate,
 			HumanSignedOutType,
 		),
-		UserAgentID: userAgentID,
+		UserAgentID:       userAgentID,
+		SessionID:         sessionID,
+		TriggeredAtOrigin: http.DomainContext(ctx).Origin(),
 	}
 }