Fix set badge tint color

[mlmorgan]

Given a button badge is behind a modally presented view controller, when the tint color of the badge is set, then the badge color will be gray instead of the set color.

One way to fix this is to utilise tintColorDidChange instead of using a didSet for tintColor.

In these before and after examples, the badge tint color is being set to red in onTraitCollectionDidChange, which is being triggered by changing from dark to light mode (or vice versa):

Before:
https://user-images.githubusercontent.com/34710656/231182379-da87b0af-b8f8-4048-876f-8ef460340db1.mp4

After:
https://user-images.githubusercontent.com/34710656/231180867-72d0c09b-6c32-43d4-a256-450c3a7b745b.mp4

The downside to this fix is that the doc comment is removed. Another fix would be to use a new var instead of overriding tintColor, but that would create breaking changes.

[msaps]

Thanks for the contribution! 😄 and sorry for the delay 🚀