feat: add api-based extension & external data tool & moderation backend (#1403)

Co-authored-by: takatost <takatost@gmail.com>

api/core/external_data_tool/base.py

@@ -0,0 +1,45 @@
+from abc import abstractmethod, ABC
+from typing import Optional
+
+from core.extension.extensible import Extensible, ExtensionModule
+
+
+class ExternalDataTool(Extensible, ABC):
+    """
+    The base class of external data tool.
+    """
+
+    module: ExtensionModule = ExtensionModule.EXTERNAL_DATA_TOOL
+
+    app_id: str
+    """the id of app"""
+    variable: str
+    """the tool variable name of app tool"""
+
+    def __init__(self, tenant_id: str, app_id: str, variable: str, config: Optional[dict] = None) -> None:
+        super().__init__(tenant_id, config)
+        self.app_id = app_id
+        self.variable = variable
+
+    @classmethod
+    @abstractmethod
+    def validate_config(cls, tenant_id: str, config: dict) -> None:
+        """
+        Validate the incoming form config data.
+
+        :param tenant_id: the id of workspace
+        :param config: the form config data
+        :return:
+        """
+        raise NotImplementedError
+
+    @abstractmethod
+    def query(self, inputs: dict, query: Optional[str] = None) -> str:
+        """
+        Query the external data tool.
+
+        :param inputs: user inputs
+        :param query: the query of chat app
+        :return: the tool query result
+        """
+        raise NotImplementedError