✨ feat(MetalRetriever.py): add MetalRetriever component to retrieve data using the Metal API

✨ feat(__init__.py): add empty __init__.py file to the retrievers directory to make it a package

src/backend/langflow/components/retrievers/MetalRetriever.py

@@ -0,0 +1,23 @@
+from typing import Optional
+from langflow import CustomComponent
+from langchain.retrievers import MetalRetriever
+from langchain.schema.retriever import BaseRetriever
+
+
+class MetalRetrieverComponent(CustomComponent):
+    display_name: str = "Metal Retriever"
+    description: str = "Retriever that uses the Metal API."
+
+    def build_config(self):
+        return {
+            "api_key": {"display_name": "API Key", "password": True},
+            "client_id": {"display_name": "Client ID", "password": True},
+            "index_id": {"display_name": "Index ID"},
+            "params": {"display_name": "Parameters", "field_type": "code"},
+            "code": {"show": False},
+        }
+
+    def build(
+        self, api_key: str, client_id: str, index_id: str, params: Optional[dict] = None
+    ) -> BaseRetriever:
+        return MetalRetriever(api_key, client_id, index_id, params=params)