[Switch] make sure wasOn is set properly

[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

Separating out a change from #1867 to reduce the footprint of that PR.

When a <Switch> is created on macOS with an initial value of on, it would not report it's change the first time you toggled it. This seems to be because an internal variable _wasOn was not set properly on macOS, which the onChange handler relied on. Comparing Appkit to UIKit, I think this is because in UIKit, setting the property on will internally call setOn:Animated, which RN overrides to set _wasOn. We had to reimplement both on and setOn:Animated for macOS. Let's just have the setter for on call setOn:Animated to fix this issue.

Changelog

Pick one each for the category and type tags:

[MACOS] [FIXED] - Make sure wasOn is set properly in Switch

Test Plan

Before (from #1867):

1.mov

After:

Screen.Recording.2023-07-05.at.10.46.08.PM.mov