refactor: Twitch PubSub client (#5059)

* Remove unused `setAccountData` function

* Move PubSub out of TwitchIrcServer and into Application

* Add changelog entry

* fix: assert feedback

* Add PubSub::unlistenPrefix as per review suggestion

* Fix tests

* quit pubsub on exit

might conflict with exit removal, so can be reverted but this shows it's possible

* Don't manually call stop on clients, it's called when the connection is closed

* nit: rename `mainThread` to `thread`

* Join in a thread!!!!!!!!

src/providers/twitch/TwitchIrcServer.hpp

@@ -18,7 +18,6 @@ namespace chatterino {
 
 class Settings;
 class Paths;
-class PubSub;
 class TwitchChannel;
 class BttvLiveUpdates;
 class SeventvEventAPI;
@@ -80,8 +79,6 @@ public:
     const ChannelPtr automodChannel;
     IndirectChannel watchingChannel;
 
-    // NOTE: We currently leak this
-    PubSub *pubsub;
     std::unique_ptr<BttvLiveUpdates> bttvLiveUpdates;
     std::unique_ptr<SeventvEventAPI> seventvEventAPI;