Fix more unit tests. (#1406)

- Randomise test order.
- Use deferred fulfilment in more places.
- Make sure to change something before awaiting the fulfilment.
- Build a fresh AppSettings after reset().
- Retry tests on failure.

ElementX/Sources/Screens/RoomDetailsScreen/RoomDetailsScreenModels.swift

@@ -219,6 +219,18 @@ extension RoomDetailsNotificationSettingsState {
         return false
     }
     
+    /// Returns `true` when the settings are loaded and `isDefault` is true.
+    var isDefault: Bool {
+        guard case let .loaded(settings) = self else { return false }
+        return settings.isDefault
+    }
+    
+    /// Returns `true` when the settings are loaded and `isDefault` is false.
+    var isCustom: Bool {
+        guard case let .loaded(settings) = self else { return false }
+        return !settings.isDefault
+    }
+    
     var isError: Bool {
         if case .error = self {
             return true