[foundation/uikit] Inline NSItemProvider_UIKitAdditions in NSItemProvider (#2538)

As suggested here: https://github.com/xamarin/xamarin-macios/pull/2527#discussion_r134670981

src/foundation.cs

@@ -9749,6 +9749,25 @@ namespace XamCore.Foundation
 		[Watch (4,0), TV (11,0), Mac (10,13), iOS (11,0)]
 		[Async, Wrap ("LoadObject (new Class (type), completionHandler)")]
 		NSProgress LoadObject (Type type, Action<INSItemProviderReading, NSError> completionHandler);
+
+#if !MONOMAC
+		// NSItemProvider_UIKitAdditions category
+
+		[NoWatch, NoTV]
+		[iOS (11,0)]
+		[NullAllowed, Export ("teamData", ArgumentSemantic.Copy)]
+		NSData TeamData { get; set; }
+
+		[NoWatch, NoTV]
+		[iOS (11,0)]
+		[Export ("preferredPresentationSize", ArgumentSemantic.Assign)]
+		CGSize PreferredPresentationSize { get; set; }
+
+		[NoWatch, NoTV]
+		[iOS (11,0)]
+		[Export ("preferredPresentationStyle", ArgumentSemantic.Assign)]
+		UIPreferredPresentationStyle PreferredPresentationStyle { get; set; }
+#endif // !MONOMAC
 	}
     
 	delegate NSProgress RegisterFileRepresentationLoadHandler ([BlockCallback] RegisterFileRepresentationCompletionHandler completionHandler);

src/uikit.cs

@@ -6942,33 +6942,6 @@ namespace XamCore.UIKit {
 		CGSize PreferredPresentationSizeForItemProvider { get; }
 	}
 
-	[iOS (11,0), TV (11,0), Watch (4,0)]
-	[Category]
-	[BaseType (typeof(NSItemProvider))]
-	interface NSItemProvider_UIKitAdditions {
-		[NoWatch, NoTV]
-		[NullAllowed, Export ("teamData", ArgumentSemantic.Copy)]
-		NSData GetTeamData ();
-
-		[NoWatch, NoTV]
-		[NullAllowed, Export ("setTeamData", ArgumentSemantic.Copy)]
-		NSData SetTeamData ();
-
-		[NoWatch, NoTV]
-		[Export ("preferredPresentationSize", ArgumentSemantic.Assign)]
-		CGSize GetPreferredPresentationSize ();
-
-		[NoWatch, NoTV]
-		[Export ("setPreferredPresentationSize", ArgumentSemantic.Assign)]
-		CGSize SetPreferredPresentationSize ();
-
-		[Export ("preferredPresentationStyle", ArgumentSemantic.Assign)]
-		UIPreferredPresentationStyle GetPreferredPresentationStyle ();
-
-		[Export ("setPreferredPresentationStyle", ArgumentSemantic.Assign)]
-		UIPreferredPresentationStyle SetPreferredPresentationStyle ();
-	}
-
 	[BaseType (typeof (NSObject))]
 	interface UIImage : NSSecureCoding
 #if !WATCH