turning a lot of includes into forward declares

src/widgets/dialogs/EmotePopup.hpp

@@ -1,13 +1,16 @@
 #pragma once
 
-#include "common/Channel.hpp"
 #include "widgets/BaseWindow.hpp"
-#include "widgets/helper/ChannelView.hpp"
 
 #include <pajlada/signals/signal.hpp>
 
 namespace chatterino {
 
+class Link;
+class ChannelView;
+class Channel;
+using ChannelPtr = std::shared_ptr<Channel>;
+
 class EmotePopup : public BaseWindow
 {
 public: