feat(ui): add necessary utils

ui/lib/utils/formatHistory.ts

@@ -0,0 +1,9 @@
+import { BaseMessage } from '@langchain/core/messages';
+
+const formatChatHistoryAsString = (history: BaseMessage[]) => {
+  return history
+    .map((message) => `${message._getType()}: ${message.content}`)
+    .join('\n');
+};
+
+export default formatChatHistoryAsString;