Editor code: tidy up BOOLs,NULLs and overrides pt6.

A few 'typedefs' replaced by 'using's
This shouldn't have any functional changes at all, just c++17 modernization
It's a part 6 of a split #2847

Signed-off-by: Nemerle <nemerle5+git@gmail.com>

Code/Editor/ViewportTitleDlg.cpp

@@ -91,7 +91,7 @@ namespace
         void ViewportInfoStatusUpdated(int newIndex);
 
     private:
-        void OnViewportInfoDisplayStateChanged(AZ::AtomBridge::ViewportInfoDisplayState state)
+        void OnViewportInfoDisplayStateChanged(AZ::AtomBridge::ViewportInfoDisplayState state) override
         {
             emit ViewportInfoStatusUpdated(static_cast<int>(state));
         }