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.go

@@ -31,6 +31,7 @@ type addOIDCApp struct {
 	ClockSkew                   time.Duration
 	AdditionalOrigins           []string
 	SkipSuccessPageForNativeApp bool
+	BackChannelLogoutURI        string
 
 	ClientID          string
 	ClientSecret      string
@@ -108,6 +109,7 @@ func (c *Commands) AddOIDCAppCommand(app *addOIDCApp) preparation.Validation {
 					app.ClockSkew,
 					trimStringSliceWhiteSpaces(app.AdditionalOrigins),
 					app.SkipSuccessPageForNativeApp,
+					app.BackChannelLogoutURI,
 				),
 			}, nil
 		}, nil
@@ -199,6 +201,7 @@ func (c *Commands) addOIDCApplicationWithID(ctx context.Context, oidcApp *domain
 		oidcApp.ClockSkew,
 		trimStringSliceWhiteSpaces(oidcApp.AdditionalOrigins),
 		oidcApp.SkipNativeAppSuccessPage,
+		strings.TrimSpace(oidcApp.BackChannelLogoutURI),
 	))
 
 	addedApplication.AppID = oidcApp.AppID
@@ -256,6 +259,7 @@ func (c *Commands) ChangeOIDCApplication(ctx context.Context, oidc *domain.OIDCA
 		oidc.ClockSkew,
 		trimStringSliceWhiteSpaces(oidc.AdditionalOrigins),
 		oidc.SkipNativeAppSuccessPage,
+		strings.TrimSpace(oidc.BackChannelLogoutURI),
 	)
 	if err != nil {
 		return nil, err