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/audio/core/events/red.py

@@ -1,5 +1,6 @@
+import asyncio
 import logging
-from typing import Mapping
+from typing import Literal, Mapping
 
 from redbot.core import commands
 from ..abc import MixinMeta
@@ -19,3 +20,37 @@ class RedEvents(MixinMeta, metaclass=CompositeMetaClass):
             self.api_interface.spotify_api.update_token(api_tokens)
         elif service_name == "audiodb":
             self.api_interface.global_cache_api.update_token(api_tokens)
+
+    async def red_delete_data_for_user(
+        self,
+        *,
+        requester: Literal["discord_deleted_user", "owner", "user", "user_strict"],
+        user_id: int,
+    ):
+
+        await self.cog_ready_event.wait()
+
+        if requester in ("discord_deleted_user", "owner"):
+            await self.playlist_api.handle_playlist_user_id_deletion(user_id)
+
+            all_equalizers = await self.config.custom("EQUALIZER").all()
+
+            collected_for_removal = []
+
+            c = 0
+            for guild_id, guild_equalizers in all_equalizers.items():
+                c += 1
+                if not c % 100:
+                    await asyncio.sleep(0)
+
+                for preset_name, preset in guild_equalizers.get("eq_presets", {}).items():
+                    c += 1
+                    if not c % 100:
+                        await asyncio.sleep(0)
+
+                    if preset.get("author", 0) == user_id:
+                        collected_for_removal.append((guild_id, preset_name))
+
+            async with self.config.custom("EQUALIZER").all() as all_eqs:
+                for guild_id, preset_name in collected_for_removal:
+                    all_eqs[str(guild_id)]["eq_presets"][preset_name]["author"] = 0xDE1