CWorldInfoSidebar: Add missing UICommon include

Gets rid of an indirect include.
Also adds a forward declaration to prevent build failures in the future.

src/Editor/WorldEditor/CWorldInfoSidebar.cpp

@@ -1,7 +1,10 @@
 #include "CWorldInfoSidebar.h"
 #include "ui_CWorldInfoSidebar.h"
-#include "CWorldEditor.h"
+
+
 #include "Editor/CEditorApplication.h"
+#include "Editor/UICommon.h"
+#include "Editor/WorldEditor/CWorldEditor.h"
 
 CWorldInfoSidebar::CWorldInfoSidebar(CWorldEditor *pEditor)
     : CWorldEditorSidebar(pEditor)

src/Editor/WorldEditor/CWorldInfoSidebar.h

@@ -8,6 +8,7 @@
 
 #include <memory>
 
+class CGameProject;
 class CWorldEditor;
 
 namespace Ui {