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

Code/Sandbox/Editor/EditorViewportWidget.cpp

@@ -659,9 +659,6 @@ CBaseObject* EditorViewportWidget::GetCameraObject() const
 //////////////////////////////////////////////////////////////////////////
 void EditorViewportWidget::OnEditorNotifyEvent(EEditorNotifyEvent event)
 {
-    static ICVar* outputToHMD = gEnv->pConsole->GetCVar("output_to_hmd");
-    AZ_Assert(outputToHMD, "cvar output_to_hmd is undeclared");
-
     switch (event)
     {
     case eNotify_OnBeginGameMode:
@@ -683,7 +680,6 @@ void EditorViewportWidget::OnEditorNotifyEvent(EEditorNotifyEvent event)
                 if (deviceInfo)
                 {
                     // Note: This may also need to adjust the viewport size
-                    outputToHMD->Set(1);
                     SetActiveWindow();
                     SetFocus();
                     SetSelected(true);
@@ -703,10 +699,6 @@ void EditorViewportWidget::OnEditorNotifyEvent(EEditorNotifyEvent event)
         if (GetIEditor()->GetViewManager()->GetGameViewport() == this)
         {
             SetCurrentCursor(STD_CURSOR_DEFAULT);
-            if (gSettings.bEnableGameModeVR)
-            {
-                outputToHMD->Set(0);
-            }
             m_bInRotateMode = false;
             m_bInMoveMode = false;
             m_bInOrbitMode = false;