NSAttributedString constants are defined in multiple places:
[iOS/Mac] Foundation’s NSAttributedString (x3 cause there are 3 declarations) + DictionaryContainer in NSAttributedString.mac.cs (missing iOS strong dictionary)
[iOS] UIKit’s UIStringAttributeKey + DictionaryContainer in NSAttributedString.iOS.cs
[Mac] AppKit’s NSStringAttributeKey + DictionaryContainer in NSStringAttributes.cs && NSAttributedString.mac.cs (edited)
Some stuff in UIKit, some in appkit, some in foundation (but duplicated Fields cause they are also in AppKit), actually in all 3 frameworks.
We have `NSStringAttributes.cs` and `NSAttributedString.mac.cs` (there seems to be some duplication).
In PR 2599 I added the new field to https://github.com/VincentDondain/xamarin-macios/blob/0c4bf1a9c5f80e9cca56a07de9e9480ce1287802/src/foundation.cs#L13185-L13255 but I’m not sure this should actually live in `foundation.cs` maybe the separation between AppKit and UIKit is the way to go.
This feels like it's just adding to the mess so we may want to simplify things (: