Remove legacy serialization and QPropertyTree (#684)

Remove:
- CryCommon/CryExtension/*
- CryCommon/Serialization/*
- Sandbox/Plugins/EditorCommon/QPropertyTree/*
- All related CryCommon interfaces
- All CrySystem implementations
- Various related Editor classes

Gems/AudioSystem/Code/Include/Editor/IAudioConnection.h

@@ -14,8 +14,6 @@
 #pragma once
 
 #include <ACETypes.h>
-#include <Serialization/IArchive.h>
-#include <Serialization/STL.h>
 
 namespace AudioControls
 {
@@ -40,10 +38,6 @@ namespace AudioControls
             return false;
         }
 
-        virtual void Serialize([[maybe_unused]] Serialization::IArchive& ar)
-        {
-        }
-
     private:
         CID m_id;
     };