Add lifecycle customisation point after logout

This will help specific deployments that need to do something custom here such
as redirect the user or call some API after Element has logged out and cleared
storage.

src/Lifecycle.ts

@@ -49,6 +49,7 @@ import {SSO_HOMESERVER_URL_KEY, SSO_ID_SERVER_URL_KEY} from "./BasePlatform";
 import ThreepidInviteStore from "./stores/ThreepidInviteStore";
 import CountlyAnalytics from "./CountlyAnalytics";
 import CallHandler from './CallHandler';
+import LifecycleCustomisations from "./customisations/Lifecycle";
 
 const HOMESERVER_URL_KEY = "mx_hs_url";
 const ID_SERVER_URL_KEY = "mx_is_url";
@@ -716,6 +717,7 @@ export async function onLoggedOut(): Promise<void> {
     dis.dispatch({action: 'on_logged_out'}, true);
     stopMatrixClient();
     await clearStorage({deleteEverything: true});
+    LifecycleCustomisations.onLoggedOutAndStorageCleared?.();
 }
 
 /**