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

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

api/extensions/ext_code_based_extension.py

@@ -0,0 +1,8 @@
+from core.extension.extension import Extension
+
+
+def init():
+    code_based_extension.init()
+
+
+code_based_extension = Extension()