Add searchapi as an alternative web search

Add config changes for SearchApi api key and engine

Add searchapi results json in testdata

backend/apps/rag/search/main.py

@@ -8,7 +8,8 @@ def get_filtered_results(results, filter_list):
         return results
     filtered_results = []
     for result in results:
-        domain = urlparse(result["url"]).netloc
+        url = result.get("url") or result.get("link", "")
+        domain = urlparse(url).netloc
         if any(domain.endswith(filtered_domain) for filtered_domain in filter_list):
             filtered_results.append(result)
     return filtered_results