Fix ColorWithSystemEffect not returning the correct base color

[chiuam]

Please select one of the following

• I am removing an existing difference between facebook/react-native and microsoft/react-native-macos 👍
• I am cherry-picking a change from Facebook's react-native into microsoft/react-native-macos 👍
• I am making a fix / change for the macOS implementation of react-native
• I am making a change required for Microsoft usage of react-native

Summary

When the colorWithSystemEffect object gets normalized, we should be calling @react-native/normalize-colors not processColor. This is a regression from 68 because in 68 we return the unprocessed color, not the noralized color object https://github.com/microsoft/react-native-macos/blob/0.68-stable/Libraries/StyleSheet/normalizeColor.js#L25

Changelog

Test Plan

Before:

After:

[Saadnajmi]

Filed this for the long term "refactor this to share more code with iOS so we don't break unintentionally in the future again"
#1846