Make destructiveRed a CupertinoDynamicColor (#141364)

`destructiveRed` is an alias for `systemRed`, but, in the definition, the precise type information is lost.

This PR gives `destructiveRed` the type `CupertinoDynamicColor` (and not the superclass `Color`) like all the other colors defined in this file.

packages/flutter/lib/src/cupertino/colors.dart

@@ -110,7 +110,7 @@ abstract final class CupertinoColors {
   /// or the foreground red theme in various native apps such as HealthKit.
   ///
   /// This is SystemRed in the iOS palette.
-  static const Color destructiveRed = systemRed;
+  static const CupertinoDynamicColor destructiveRed = systemRed;
 
   /// A blue color that can adapt to the given [BuildContext].
   ///