add @testing-library/user-event and create tests for external-knowledge-base/ (#29323)

Co-authored-by: CodingOnStar <hanxujiang@dify.ai>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

web/package.json

@@ -168,6 +168,7 @@
     "@testing-library/dom": "^10.4.1",
     "@testing-library/jest-dom": "^6.9.1",
     "@testing-library/react": "^16.3.0",
+    "@testing-library/user-event": "^14.6.1",
     "@types/jest": "^29.5.14",
     "@types/js-cookie": "^3.0.6",
     "@types/js-yaml": "^4.0.9",