Add property for corner radius value of all curved iOS devices

[TimOliver]

Hey folks!

I'm really digging this library! Fantastic work!

I have an idea for a feature. I'm happy to file a PR myself, but I thought I'd ask if it's a good idea first.

A lot of iOS' system level UI components round their UI to match the physical curve of notched/Dynamic Island screens. While accessing the corner radius of the screen is possible via a private API, this library looks like a great way to expose that information in a more "legal" way. :)

Would anyone be interested if I filed a PR to add the corner radius value of all of the rounded iOS devices? :)

Thanks!