[Docs] Add explainer for gotchas with NSView based native components

[Saadnajmi]

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

While working on microsoft/fluentui-react-native#3026, I found a couple of "gotchas" while writing a native component for NSVisualEffectView. This change attempts to documents those gotchas so that others can benefit. Special thanks to @lenaic who figured out the hit testing issue.

Changelog

[GENERAL] [ADDED] - Add documentation for gotchas with NSView based native components

Test Plan

N/A

[Saadnajmi]

Marking as draft to see if I can update RCTUIView hitTest instead