fix: preserve default menu icon colors on iOS new arch

[michaelpomogajko]

Summary

• stop forwarding imageColor and titleColor from the New Architecture bridge when they were not explicitly set in JS
• keep the existing behavior for explicitly provided colors

Root cause

In the Fabric/New Architecture path, codegen turns optional imageColor and titleColor fields into plain integer props with a default value of 0. MenuView.mm always forwarded those values into the Objective-C action dictionaries, so iOS treated missing imageColor as a real color and tinted SF Symbols to an invisible color.

This shows up as menu titles rendering correctly while icons disappear entirely on iOS New Architecture, even when the JS action config follows the documented API.

Validation

• reproduced in an Expo 55 / React Native 0.83 app using @react-native-menu/menu 2.0.0
• verified that icons render again after omitting unset color props from the New Arch bridge
• change is scoped to ios/NewArch/MenuView.mm only