feat: delete local backups when signing out

app/assets/javascripts/ui_models/application.ts

@@ -53,7 +53,7 @@ export class WebApplication extends SNApplication {
     private $compile: angular.ICompileService,
     scope: angular.IScope,
     defaultSyncServerHost: string,
-    private bridge: Bridge,
+    public bridge: Bridge,
   ) {
     super(
       bridge.environment,
@@ -169,6 +169,11 @@ export class WebApplication extends SNApplication {
     return angular.element(document.getElementById(this.identifier)!);
   }
 
+  async signOutAndDeleteLocalBackups(): Promise<void> {
+    await this.bridge.deleteLocalBackups();
+    return this.signOut();
+  }
+
   presentPasswordModal(callback: () => void) {
     const scope = this.scope!.$new(true) as InputModalScope;
     scope.type = "password";