This is so that new channel types added by Discord (that may or may not
support the features we need for proxying to work) don't throw piles of
error codes at users when they try to proxy.
Handling of both blacklists was inconsistent when dealing with threads:
- proxy blacklist of root channel blacklists all threads
- log blacklist of root channel _did not apply_ to threads
- couldn't proxy blacklist threads while leaving root channel proxyable
This change fixes the inconsistencies:
- proxy _and_ log blacklist of root channel affects all threads
- now able to individually proxy/log blacklist threads, with root
channel unaffected
- remove Cluster.User
- remove Cluster.Application (it was only being used as an alternative to Cluster.User for some reason)
- move Bot.PermissionsIn to DiscordCacheExtensions
this breaks logging bot permissions to Sentry.
we haven't had a need to check those recently (permissions issues were because of broken cache), so this is fine for now
this should be re-added in the future though
