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

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

api/core/extension/extension.py

@@ -0,0 +1,47 @@
+from core.extension.extensible import ModuleExtension, ExtensionModule
+from core.external_data_tool.base import ExternalDataTool
+from core.moderation.base import Moderation
+
+
+class Extension:
+    __module_extensions: dict[str, dict[str, ModuleExtension]] = {}
+
+    module_classes = {
+        ExtensionModule.MODERATION: Moderation,
+        ExtensionModule.EXTERNAL_DATA_TOOL: ExternalDataTool
+    }
+
+    def init(self):
+        for module, module_class in self.module_classes.items():
+            self.__module_extensions[module.value] = module_class.scan_extensions()
+
+    def module_extensions(self, module: str) -> list[ModuleExtension]:
+        module_extensions = self.__module_extensions.get(module)
+
+        if not module_extensions:
+            raise ValueError(f"Extension Module {module} not found")
+
+        return list(module_extensions.values())
+
+    def module_extension(self, module: ExtensionModule, extension_name: str) -> ModuleExtension:
+        module_extensions = self.__module_extensions.get(module.value)
+
+        if not module_extensions:
+            raise ValueError(f"Extension Module {module} not found")
+
+        module_extension = module_extensions.get(extension_name)
+
+        if not module_extension:
+            raise ValueError(f"Extension {extension_name} not found")
+
+        return module_extension
+
+    def extension_class(self, module: ExtensionModule, extension_name: str) -> type:
+        module_extension = self.module_extension(module, extension_name)
+        return module_extension.extension_class
+
+    def validate_form_schema(self, module: ExtensionModule, extension_name: str, config: dict) -> None:
+        module_extension = self.module_extension(module, extension_name)
+        form_schema = module_extension.form_schema
+
+        # TODO validate form_schema