Sync notifications using WorkManager (#5545)

* Initial implementation of notification sync using `WorkManager`

* Use custom `MetroWorkerFactory` to allow assisted injection in WorkManager Workers

* Add tests for `FetchNotificationWorker`. Create `FakeNotificationResolverQueue` to help testing.

* Add more tests, fix Konsist checks

* Add tests for `SyncNotificationWorkManagerRequest`

* Simplify `FakeNotificationResolverQueue`

libraries/featureflag/api/src/main/kotlin/io/element/android/libraries/featureflag/api/FeatureFlags.kt

@@ -109,4 +109,12 @@ enum class FeatureFlags(
         defaultValue = { false },
         isFinished = false,
     ),
+    SyncNotificationsWithWorkManager(
+        key = "feature.sync_notifications_with_workmanager",
+        title = "Sync notifications with WorkManager",
+        description = "Use WorkManager to schedule notification sync tasks when a push is received." +
+            " This should improve reliability and battery usage.",
+        defaultValue = { false },
+        isFinished = false,
+    ),
 }