Adding Document Sets (#477)

Adds:
- name for connector credential pairs + frontend changes to start populating this field
- document set table migration
- during indexing, document sets are now checked and inserted into Vespa
- background job to check if document sets need to be synced
- document set management APIs
- document set management dashboard in the UI

web/src/app/admin/documents/sets/hooks.tsx

@@ -0,0 +1,13 @@
+import { fetcher } from "@/lib/fetcher";
+import { DocumentSet } from "@/lib/types";
+import useSWR, { mutate } from "swr";
+
+export const useDocumentSets = () => {
+  const url = "/api/manage/document-set";
+  const swrResponse = useSWR<DocumentSet<any, any>[]>(url, fetcher);
+
+  return {
+    ...swrResponse,
+    refreshDocumentSets: () => mutate(url),
+  };
+};