Show error screens in group calls

Element Call now sends a 'close' widget action when the widget is ready to close. Usually this will be sent immediately after the 'hangup' action, but it could be sent later if the widget wants to present an error screen before closing. So by listening to the 'close' action rather than the 'hangup' action, we get to see these error screens.

ElementX/Sources/Services/ElementCall/ElementCallWidgetDriver.swift

@@ -17,6 +17,7 @@ struct ElementCallWidgetMessage: Codable {
 
     enum Action: String, Codable {
         case hangup = "im.vector.hangup"
+        case close = "io.element.close"
         case mediaState = "io.element.device_mute"
     }
 
@@ -181,6 +182,8 @@ class ElementCallWidgetDriver: WidgetCapabilitiesProvider, ElementCallWidgetDriv
             if widgetMessage.direction == .fromWidget {
                 switch widgetMessage.action {
                 case .hangup:
+                    break
+                case .close:
                     actionsSubject.send(.callEnded)
                 case .mediaState:
                     guard let audioEnabled = widgetMessage.data.audioEnabled,