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/user_human.go

@@ -628,16 +628,21 @@ func createAddHumanEvent(ctx context.Context, aggregate *eventstore.Aggregate, h
 	return addEvent
 }
 
-func (c *Commands) HumansSignOut(ctx context.Context, agentID string, userIDs []string) error {
+type HumanSignOutSession struct {
+	ID     string
+	UserID string
+}
+
+func (c *Commands) HumansSignOut(ctx context.Context, agentID string, sessions []HumanSignOutSession) error {
 	if agentID == "" {
 		return zerrors.ThrowInvalidArgument(nil, "COMMAND-2M0ds", "Errors.User.UserIDMissing")
 	}
-	if len(userIDs) == 0 {
+	if len(sessions) == 0 {
 		return zerrors.ThrowInvalidArgument(nil, "COMMAND-M0od3", "Errors.User.UserIDMissing")
 	}
 	events := make([]eventstore.Command, 0)
-	for _, userID := range userIDs {
-		existingUser, err := c.getHumanWriteModelByID(ctx, userID, "")
+	for _, session := range sessions {
+		existingUser, err := c.getHumanWriteModelByID(ctx, session.UserID, "")
 		if err != nil {
 			return err
 		}
@@ -647,7 +652,9 @@ func (c *Commands) HumansSignOut(ctx context.Context, agentID string, userIDs []
 		events = append(events, user.NewHumanSignedOutEvent(
 			ctx,
 			UserAggregateFromWriteModel(&existingUser.WriteModel),
-			agentID))
+			agentID,
+			session.ID,
+		))
 	}
 	if len(events) == 0 {
 		return nil