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/core/dev_commands.py

@@ -33,6 +33,13 @@ START_CODE_BLOCK_RE = re.compile(r"^((```py)(?=\s)|(```))")
 class Dev(commands.Cog):
     """Various development focused utilities."""
 
+    async def red_delete_data_for_user(self, **kwargs):
+        """
+        Because despite my best efforts to advise otherwise,
+        people use ``--dev`` in production
+        """
+        return
+
     def __init__(self):
         super().__init__()
         self._last_result = None