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/widgets/Window.cpp

@@ -281,7 +281,7 @@ void Window::addDebugStuff(HotkeyController::HotkeyMap &actions)
                     ->toInner<PubSubCommunityPointsChannelV1Message>();
 
             app->twitch->addFakeMessage(getSampleChannelRewardIRCMessage());
-            app->twitch->pubsub->signals_.pointReward.redeemed.invoke(
+            getIApp()->getTwitchPubSub()->pointReward.redeemed.invoke(
                 oInnerMessage->data.value("redemption").toObject());
             alt = !alt;
         }
@@ -292,7 +292,7 @@ void Window::addDebugStuff(HotkeyController::HotkeyMap &actions)
             auto oInnerMessage =
                 oMessage->toInner<PubSubMessageMessage>()
                     ->toInner<PubSubCommunityPointsChannelV1Message>();
-            app->twitch->pubsub->signals_.pointReward.redeemed.invoke(
+            getIApp()->getTwitchPubSub()->pointReward.redeemed.invoke(
                 oInnerMessage->data.value("redemption").toObject());
             alt = !alt;
         }