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/project_application_oidc_model.go

@@ -36,6 +36,7 @@ type OIDCApplicationWriteModel struct {
 	State                    domain.AppState
 	AdditionalOrigins        []string
 	SkipNativeAppSuccessPage bool
+	BackChannelLogoutURI     string
 	oidc                     bool
 }
 
@@ -165,6 +166,7 @@ func (wm *OIDCApplicationWriteModel) appendAddOIDCEvent(e *project.OIDCConfigAdd
 	wm.ClockSkew = e.ClockSkew
 	wm.AdditionalOrigins = e.AdditionalOrigins
 	wm.SkipNativeAppSuccessPage = e.SkipNativeAppSuccessPage
+	wm.BackChannelLogoutURI = e.BackChannelLogoutURI
 }
 
 func (wm *OIDCApplicationWriteModel) appendChangeOIDCEvent(e *project.OIDCConfigChangedEvent) {
@@ -213,6 +215,9 @@ func (wm *OIDCApplicationWriteModel) appendChangeOIDCEvent(e *project.OIDCConfig
 	if e.SkipNativeAppSuccessPage != nil {
 		wm.SkipNativeAppSuccessPage = *e.SkipNativeAppSuccessPage
 	}
+	if e.BackChannelLogoutURI != nil {
+		wm.BackChannelLogoutURI = *e.BackChannelLogoutURI
+	}
 }
 
 func (wm *OIDCApplicationWriteModel) Query() *eventstore.SearchQueryBuilder {
@@ -254,6 +259,7 @@ func (wm *OIDCApplicationWriteModel) NewChangedEvent(
 	clockSkew time.Duration,
 	additionalOrigins []string,
 	skipNativeAppSuccessPage bool,
+	backChannelLogoutURI string,
 ) (*project.OIDCConfigChangedEvent, bool, error) {
 	changes := make([]project.OIDCConfigChanges, 0)
 	var err error
@@ -303,6 +309,9 @@ func (wm *OIDCApplicationWriteModel) NewChangedEvent(
 	if wm.SkipNativeAppSuccessPage != skipNativeAppSuccessPage {
 		changes = append(changes, project.ChangeSkipNativeAppSuccessPage(skipNativeAppSuccessPage))
 	}
+	if wm.BackChannelLogoutURI != backChannelLogoutURI {
+		changes = append(changes, project.ChangeBackChannelLogoutURI(backChannelLogoutURI))
+	}
 
 	if len(changes) == 0 {
 		return nil, false, nil