Make migration an asynchronous task (#4666)

* Add failed state and error to Job
* Move migration code
* Add websocket monitor
* Make migrate a job managed task

ui/v2.5/src/ConnectionMonitor.tsx

@@ -0,0 +1,34 @@
+import { useEffect, useState } from "react";
+import { getWSClient, useWSState } from "./core/StashService";
+import { useToast } from "./hooks/Toast";
+import { useIntl } from "react-intl";
+
+export const ConnectionMonitor: React.FC = () => {
+  const Toast = useToast();
+  const intl = useIntl();
+
+  const { state } = useWSState(getWSClient());
+  const [cachedState, setCacheState] = useState<typeof state>(state);
+
+  useEffect(() => {
+    if (cachedState === "connecting" && state === "error") {
+      Toast.error(
+        intl.formatMessage({
+          id: "connection_monitor.websocket_connection_failed",
+        })
+      );
+    }
+
+    if (state === "connected" && cachedState === "error") {
+      Toast.success(
+        intl.formatMessage({
+          id: "connection_monitor.websocket_connection_reestablished",
+        })
+      );
+    }
+
+    setCacheState(state);
+  }, [state, cachedState, Toast, intl]);
+
+  return null;
+};