Begin work on a data request API (#4045)

[Core] Data Deletion And Disclosure APIs

 - Adds a Data Deletion API
   - Deletion comes in a few forms based on who is requesting
   - Deletion must be handled by 3rd party
 - Adds a Data Collection Disclosure Command
   - Provides a dynamically generated statement from 3rd party
   extensions
 - Modifies the always available commands to be cog compatible
   - Also prevents them from being unloaded accidentally

redbot/cogs/bank/bank.py

@@ -134,3 +134,7 @@ class Bank(commands.Cog):
         )
 
     # ENDSECTION
+
+    async def red_delete_data_for_user(self, **kwargs):
+        """ Nothing to delete """
+        return