Added support for Twitch's Chat Replies (#3722)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/widgets/splits/Split.hpp

@@ -15,6 +15,7 @@
 namespace chatterino {
 
 class ChannelView;
+class MessageThread;
 class SplitHeader;
 class SplitInput;
 class SplitContainer;
@@ -74,6 +75,8 @@ public:
 
     void setContainer(SplitContainer *container);
 
+    void setInputReply(const std::shared_ptr<MessageThread> &reply);
+
     static pajlada::Signals::Signal<Qt::KeyboardModifiers>
         modifierStatusChanged;
     static Qt::KeyboardModifiers modifierStatus;