Execute chunk tasks while waiting for chunk load in isChunkGenerated

this shouldn't be needed as we are requesting EMPTY status, however there is a deeper issue that we will just work around for now

fixes #10916

patches/server/Fix-CraftWorld-isChunkGenerated.patch

@@ -31,6 +31,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +        ca.spottedleaf.moonrise.patches.chunk_system.ChunkSystem.scheduleChunkLoad(
 +            this.world, x, z, false, ChunkStatus.EMPTY, false, ca.spottedleaf.concurrentutil.executor.standard.PrioritisedExecutor.Priority.NORMAL, future::complete
 +        );
++        world.getChunkSource().mainThreadProcessor.managedBlock(future::isDone);
 +        return future.thenApply(c -> {
 +            if (c != null) {
 +                return c.getPersistedStatus() == ChunkStatus.FULL;