refactor chat connections and allow dynamically joining chats

[Felk]

• entire co-stream-inputs feature can be enabled using CoStreamInputsEnabled (inside twitch connection config) (default false)
• !join and !leave are implemented
• !join only works when the user is live (configurable via CoStreamInputsOnlyLive, default true)
• if CoStreamInputsOnlyLive is set to true, automatically leaves channgels that are no longer live
• channels joined this way are only monitored for mode-specific tasks, for runmode this means only inputs. No modbot or commands.
• only a message after !join and a message after !leave are posted in the target chats, otherwise the bot is quiet there
• inputs from TPP-banned users are ignored from all channels
• anarchy inputs got a new "channel" field that is null for tpp and populated with a channel name for foreign inputs
• !join and !leave are persisted across core restarts
• It ignores co-stream inputs while the main channel is in emote-only mode
• channel icon URLs for the channels provided
• (?) !leaveall command
  • could just set CoStreamInputsEnabled to false after the event and it stops joining other channels
• if TPP’s channel is in slow mode, it should not accept inputs at higher speed from anywhere else
• !left and !right still work

[Felk]

Need to fix this bit if/when TwitchLib/TwitchLib.Api#386 is merged and available on nuget via a prerelease

[Felk]

I've disabled twitch-native replies for now in 620b440 until we can use the API for them again. So we need to also revert 620b440 once this is fixed