fix(android): implement getDeliveredNotifications and removeDeliveredNotifications

[p7g]

This PR implements the PushNotifications plugin getDeliveredNotifications and removeDeliveredNotifications methods.

The fields available on the objects returned by getDeliveredNotifications are a subset of those available on iOS, but otherwise the behaviour should be the same.

[macdja38]

Looks good!

[trytuna]

This is 23 days old. Can we please merge that?

[jcesarmobile]

How I'm supposed to use the removeDeliveredNotifications? If I first use getDeliveredNotifications and pass the result to removeDeliveredNotifications, all the ids are 0, so doesn't remove the notifications.

For local notifications it works since we set the id, but it's confusing since the PR is about Push notifications

[p7g]

@jcesarmobile In my use-case I have a subclass of FirebaseMessagingService that sets the IDs of incoming notifications. I understand that not everyone will want to have this, but I think the problem of IDs being 0 is a different issue than the one this PR addresses.

[jcesarmobile]

yeah, but on a regular Capacitor app this will happen, and I'm concerned about users complaining about it

[p7g]

I think that having these methods implemented is better than not.

I agree that users may encounter the issue you mentioned, but we can make a new issue to find out why the IDs of the notifications are 0.

[jcesarmobile]

ok, looks good