Allow repeated notification notification messages (F-Droid)

### Your use case

#### What would you like to do?
In the case where there is a notification on the screen, and the application is completely exited (including crash), then push again after the next startup (also includes boot automatically starting). Also allow setting intervals for a certain time repeated push notification.

#### Why would you like to do it?
This may be used to resolve: After the application is restarted (including manually restarting because the application crashes, or starts automatically), there is an unread message but does not push a notification.

#### How would you like to achieve it?
n/a

### Have you considered any alternatives?

n/a

### Additional context

Reproduce the steps:
1. A sends a message to B;
2. At this point B receives the push notification of this message, but do not clear the notification;
3. B forcibly stop the application (simulation application crash), at this time, the notice will disappear;
4. B restart the app (or because the application caused by restarting the phone is automatically activated). Enter the application still has unread messages, but there is no push notification.