Fix AccountSwtichingContainerViewController not sending sceneDidEnterBackground to children

Tusker/Screens/Main/AccountSwitchingContainerViewController.swift

@@ -89,3 +89,11 @@ extension AccountSwitchingContainerViewController: TuskerRootViewController {
         root.performSearch(query: query)
     }
 }
+
+extension AccountSwitchingContainerViewController: BackgroundableViewController {
+    func sceneDidEnterBackground() {
+        if let backgroundable = root as? BackgroundableViewController {
+            backgroundable.sceneDidEnterBackground()
+        }
+    }
+}