Massage includes some more (#4294)

* Add `<functional>` include to QStringHash.hpp

This ensures the base `std::hash` template is declared before this
specialization

* Add missing includes to `src/providers/twitch/TwitchAccountManager.hpp`

* Move explicit HelixChatters constructor to the source file

* Remove unused includes & add used includes to NicknamesModel.hpp

* NicknamesModel.hpp: Remove `virtual` when `override` is used

* Add missing QStringHash include to TwitchEmotes.cpp

* Add missing includes to various files

* Print Qt version in cmake step

Technically unrelated, but I'm sneaking it in

* Add changelog entry

src/widgets/splits/ClosedSplits.hpp

@@ -6,6 +6,7 @@
 #include <deque>
 #include <mutex>
 #include <utility>
+#include <vector>
 
 namespace chatterino {
 

src/widgets/splits/InputCompletionItem.hpp

@@ -3,6 +3,7 @@
 #include "widgets/listview/GenericListItem.hpp"
 
 #include <functional>
+#include <memory>
 
 namespace chatterino {
 

src/widgets/splits/InputCompletionPopup.hpp

@@ -4,6 +4,7 @@
 #include "widgets/listview/GenericListModel.hpp"
 
 #include <functional>
+#include <memory>
 
 namespace chatterino {