Send every download status change to the subscriber (#684)

Flow::stateIn has "Strong equality-based conflation" (see documentation).
Thus, it omits every value in case it's equal to the previous one.
Since the DownloadManger::getStatus function returns a status with a queue, that contains all current "DownloadChapters" by reference, the equality check was always true.
Thus, progress changes of downloads were never sent to subscribers.
Subscriber were only notified about finished downloads (size of queue changed) or downloader status changes

server/src/main/kotlin/suwayomi/tachidesk/graphql/queries/DownloadQuery.kt

@@ -1,11 +1,16 @@
 package suwayomi.tachidesk.graphql.queries
 
+import kotlinx.coroutines.flow.first
 import suwayomi.tachidesk.graphql.types.DownloadStatus
 import suwayomi.tachidesk.manga.impl.download.DownloadManager
+import suwayomi.tachidesk.server.JavalinSetup.future
+import java.util.concurrent.CompletableFuture
 
 class DownloadQuery {
 
-    fun downloadStatus(): DownloadStatus {
-        return DownloadStatus(DownloadManager.status.value)
+    fun downloadStatus(): CompletableFuture<DownloadStatus> {
+        return future {
+            DownloadStatus(DownloadManager.status.first())
+        }
     }
 }