refactor: make chatter list its own widget (#6365)

src/widgets/ChatterListWidget.hpp

@@ -0,0 +1,22 @@
+#pragma once
+
+#include "widgets/BaseWindow.hpp"
+
+#include <QString>
+#include <QWidget>
+
+namespace chatterino {
+
+class TwitchChannel;
+
+class ChatterListWidget : public BaseWindow
+{
+    Q_OBJECT
+
+public:
+    ChatterListWidget(const TwitchChannel *twitchChannel, QWidget *parent);
+
+    Q_SIGNAL void userClicked(QString userLogin);
+};
+
+}  // namespace chatterino