refactor: turn StreamerMode into a singleton(-like thing) (#5216)

src/providers/twitch/TwitchChannel.cpp

@@ -35,6 +35,7 @@
 #include "providers/twitch/TwitchMessageBuilder.hpp"
 #include "singletons/Emotes.hpp"
 #include "singletons/Settings.hpp"
+#include "singletons/StreamerMode.hpp"
 #include "singletons/Toasts.hpp"
 #include "singletons/WindowManager.hpp"
 #include "util/Helpers.hpp"
@@ -180,7 +181,7 @@ TwitchChannel::TwitchChannel(const QString &name)
 
             // Notify on all channels with a ping sound
             if (getSettings()->notificationOnAnyChannel &&
-                !(isInStreamerMode() &&
+                !(getIApp()->getStreamerMode()->isEnabled() &&
                   getSettings()->streamerModeSuppressLiveNotifications))
             {
                 getIApp()->getNotifications()->playSound();