sharding (blacklists): Blacklist shard support.

Moved the `user_blacklist` and `guild_blacklist` to a client TTL cache.

bot/modules/workout/tracker.py

@@ -170,7 +170,7 @@ async def workout_voice_tracker(client, member, before, after):
 
     if member.bot:
         return
-    if member.id in client.objects['blacklisted_users']:
+    if member.id in client.user_blacklist():
         return
     if member.id in client.objects['ignored_members'][member.guild.id]:
         return