[Push] Show notification on push notification (until sync is started)

[ArnyminerZ]

Purpose

It can happen that a PUSH notification is received, but the app actually doesn't have access to the internet, so the synchronization is not started immediately. A notification will be shown to tell the user that the sync is pending. It should be hidden when the synchronization starts.

Short description

Added a new parameter to the enqueue functions, to tell them whether the schedule is from a push notification or not. If it is, a notification is shown using PushNotificationManager, which is shown until the sync is started.

Checklist

• The PR has a proper title, description and label.
• I have self-reviewed the PR.
• I have added documentation to complex functions and functions that can be used by other modules.
• I have added reasonable tests or consciously decided to not add tests.

Depends on: #1056

[rfc2822]

Nice, will be cool to finally get the notifications :)

A few comments though…

[ArnyminerZ]

@rfc2822 I'm not sure how to get an instance of PushNotificationManager from here, since it's in the companion, should we pass it as an argument? Doesn't sound really good

Edit: here*

davx5-ose/app/src/main/kotlin/at/bitfire/davdroid/sync/worker/OneTimeSyncWorker.kt

Lines 154 to 160 in e210448

	// Show notification if called by push
	// FIXME: Inject PushNotificationManager
	if (isPush) {
	PushNotificationManager.notify(context, account, authority)
	}

[rfc2822]

We could have used a custom entry point for the companion object. However I think there shouldn't be too much logic in companion object anyway, so I have prepared a new class in #1056. That one is useable with DI.

[rfc2822]

Looks very promising – only minor comments.

[rfc2822]

Great, looking forward to (not) see the notifications 👍🏻