Restart notification service after closing the app

[ghost]

Describe the bug

After closing the app directly (or using task killer) on smartphones without Google Play Services the notification service doesn't restart and as a result there are no notifications.

To Reproduce

Steps to reproduce the behavior:

1. Open the Element app.
2. Close the Element app.
3. Write a message to that app using another device.
4. See no notifications.

Expected behavior

Receive push notifications.

Screenshots

After opening the app we can see running Element process.

But after closing the app there is no process and that's why there are no notifications

Smartphone (please complete the following information):

• Device: Meizu M3 Note
• OS: Android 7.0, Flyme 6.3.5.0A

Additional context

• App version and store 1.1.8 - F-Droid
• Homeserver: matrix.org
• No Google Play Services

[ouchadam]

Fixed by #4298 in 1.3.7