[FancyZones] Editor multi monitor support (#6562)

Co-authored-by: Enrico Giordani <enrico.giordani@gmail.com>
Co-authored-by: Enrico Giordani <enricogior@users.noreply.github.com>

src/modules/fancyzones/tests/UnitTests/Util.h

@@ -57,6 +57,7 @@ namespace Helpers
 {
     std::wstring GuidToString(const GUID& guid);
     std::wstring CreateGuidString();
+    std::optional<GUID> StringToGuid(const std::wstring& str);
 }
 
 template<>