feat: Support Password Access for ElasticSearch (#1072)

### What problem does this PR solve?

Using password authentication to access ElasticSearch is essential,
especially in a production environment.

This PR will enable password access support.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

rag/utils/es_conn.py

@@ -28,6 +28,8 @@ class ESConnection:
             try:
                 self.es = Elasticsearch(
                     settings.ES["hosts"].split(","),
+                    basic_auth=(settings.ES["username"], settings.ES["password"]) if "username" in settings.ES and "password" in settings.ES else None,
+                    verify_certs=False,
                     timeout=600
                 )
                 if self.es: