server: Add retries to the SQSSeederTask

Don't stop consuming messages when the connection to SQS is lost,
instead, retry to connect.

server/app/com/xsn/explorer/tasks/SQSSeederTask.scala

@@ -40,17 +40,22 @@ class SQSSeederTask @Inject() (
   def run(): Unit = {
     logger.info("Starting seeder")
 
+    def f(): Unit = {
       SqsSource(config.queueUrl, settings)
           .runWith(Sink.foreach(handleMessage))
           .onComplete {
             case Failure(ex) =>
-            logger.error("Failed to stream SQS messages", ex)
+              logger.error("Failed to stream SQS messages, restarting seeder", ex)
+              f()
 
             case Success(_) =>
               logger.info("SQS stream completed")
           }
     }
 
+    f()
+  }
+
   private def handleMessage(message: Message): Unit = {
     def onBlockhash(blockhash: Blockhash) = {
       val result = blockEventsProcessor.newLatestBlock(blockhash)