`CupertinoContextMenuAction` should have a `trailing` widget rather than just an `IconData trailingIcon`

## Use case

Now we can't change the icon color or use others widget for trailing

## Proposal

https://github.com/flutter/flutter/blob/9e0df259df9c521d0ffbdf5ba664f6ab30143884/packages/flutter/lib/src/cupertino/context_menu_action.dart#L46

`IconData trailingIcon` -> `Widget trailing`