NSOrderedCollectionDifference binding in Xcode 13 has issue with generic MonoPInvokeCallback and generator

As part of Xcode 13's Foundation changes (originally in https://github.com/xamarin/xamarin-macios/pull/13328 but later in Xcode 14) this callback is needed:

```
internal delegate NSOrderedCollectionDifference? NSOrderedCollectionDifferenceGetDifferenceHandlerProxy (IntPtr blockLiteral, /* NSOrderedCollectionChange */ IntPtr change);
static readonly NSOrderedCollectionDifferenceGetDifferenceHandlerProxy static_ChangeAllback = GetDiffHandler;

[MonoPInvokeCallback (typeof (NSOrderedCollectionDifferenceGetDifferenceHandlerProxy))]
static NSOrderedCollectionDifference? GetDiffHandler (IntPtr block, IntPtr change)
```

However, both generator.cs and the cecil test `MonoPInvokeCallback` do not like the generic `` portion.

I removed it, and then the generator, cecil test, and Manuel's monotouch tests all pass however, we are not certain that is correct.

The base collection has:

```
public sealed partial class NSOrderedCollectionDifference : NSOrderedCollectionDifference
where TKey : class, INativeObject {
```

So it can in theory have INativeObjects that are not NSObjects.

Manuel and I were not confident, so we are disabling those bindings with this issue tracking.