Crash when receiving a message from FCM but battery usage is restricted

[Hocuri]

Steps to reproduce:

• Use a chatmail account and a DC build with Google Play services enabled
• In the system settings, enable "Apps -> Delta Chat -> App Battery usage -> Restricted"
• Swipe away DC so that it's not running in the background
• Receive a message

The crash, as reported via the Google Play Console:

Exception android.app.ForegroundServiceStartNotAllowedException: startForegroundService() not allowed due to mAllowStartForeground false: service chat.delta/org.thoughtcrime.securesms.service.FetchForegroundService
  at android.app.ForegroundServiceStartNotAllowedException$1.createFromParcel (ForegroundServiceStartNotAllowedException.java:54)
  at android.app.ForegroundServiceStartNotAllowedException$1.createFromParcel (ForegroundServiceStartNotAllowedException.java:50)
  at android.os.Parcel.readParcelableInternal (Parcel.java:4775)
  at android.os.Parcel.readParcelable (Parcel.java:4743)
  at android.os.Parcel.createExceptionOrNull (Parcel.java:3006)
  at android.os.Parcel.createException (Parcel.java:2995)
  at android.os.Parcel.readException (Parcel.java:2978)
  at android.os.Parcel.readException (Parcel.java:2920)
  at android.app.IActivityManager$Stub$Proxy.startService (IActivityManager.java:5335)
  at android.app.ContextImpl.startServiceCommon (ContextImpl.java:1894)
  at android.app.ContextImpl.startForegroundService (ContextImpl.java:1870)
  at android.content.ContextWrapper.startForegroundService (ContextWrapper.java:822)
  at androidx.core.content.ContextCompat$Api26Impl.startForegroundService (ContextCompat.java:1128)
  at androidx.core.content.ContextCompat.startForegroundService (ContextCompat.java:700)
  at org.thoughtcrime.securesms.service.FetchForegroundService.start (FetchForegroundService.java:36)
  at org.thoughtcrime.securesms.notifications.FcmReceiveService.onMessageReceived (FcmReceiveService.java:94)
  at com.google.firebase.messaging.FirebaseMessagingService.dispatchMessage (FirebaseMessagingService.java:243)
  at com.google.firebase.messaging.FirebaseMessagingService.passMessageIntentToSdk (FirebaseMessagingService.java:193)
  at com.google.firebase.messaging.FirebaseMessagingService.handleMessageIntent (FirebaseMessagingService.java:179)
  at com.google.firebase.messaging.FirebaseMessagingService.handleIntent (FirebaseMessagingService.java:168)
  at com.google.firebase.messaging.EnhancedIntentService.lambda$processIntent$0$com-google-firebase-messaging-EnhancedIntentService (EnhancedIntentService.java:82)
  at com.google.firebase.messaging.EnhancedIntentService$$ExternalSyntheticLambda0.run (Unknown Source:6)
  at java.util.concurrent.ThreadPoolExecutor.runWorker (ThreadPoolExecutor.java:1145)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run (ThreadPoolExecutor.java:644)
  at com.google.android.gms.common.util.concurrent.zza.run (com.google.android.gms:play-services-basement@@18.3.0:2)
  at java.lang.Thread.run (Thread.java:1012)

The problem is that we're not allowed to start a foreground service if battery usage is "restricted".