When a property that returns an NSNumber array is marked with the BindAs
attribute, the bgen code generator uses the following pattern:

```csharp
NativeHandle retvalarrtmp;
ret = ((retvalarrtmp = global::ObjCRuntime.Messaging.NativeHandle_objc_msgSend (this.Handle, Selector.GetHandle ("sourceSampleDataTrackIDs"))) == IntPtr.Zero ? null! : (NSArray.ArrayFromHandleFunc <int> (retvalarrtmp, ptr => {
  using (var num = Runtime.GetNSObject<NSNumber> (ptr)!) {
    return (int) num.Int32Value;
  }
}, false)));
```
This code can be simplified to use a static group method. So that it
looks like:
```csharp
NativeHandle retvalarrtmp;
ret = ((retvalarrtmp = global::ObjCRuntime.Messaging.NativeHandle_objc_msgSend (this.Handle, Selector.GetHandle ("sourceSampleDataTrackIDs"))) == IntPtr.Zero ? null! : (NSArray.ArrayFromHandleFunc <int> (retvalarrtmp, NSNumber.ToInt32, false)));
```
A seasoned C# developer would mention that in C# 10 and under using method groups
(specially static ones) alocates more memory than using lambdas (lambdas were cached,
static methods were not, see dotnet/roslyn#5835).
Alas, this is not longer the case after dotnet/roslyn#58288
which means that the memory usage is the same allowing us to clean our generated code.

Using static group methods also opens the door to other possible
improvements mentioned in the roslyn PR.

PS: This is some extra work we are doing to make the generated code
simpler before we move to rgen.

When a property that returns an NSNumber array is marked with the BindAs
attribute, the bgen code generator uses the following pattern:

```csharp
NativeHandle retvalarrtmp;
ret = ((retvalarrtmp = global::ObjCRuntime.Messaging.NativeHandle_objc_msgSend (this.Handle, Selector.GetHandle ("sourceSampleDataTrackIDs"))) == IntPtr.Zero ? null! : (NSArray.ArrayFromHandleFunc <int> (retvalarrtmp, ptr => {
  using (var num = Runtime.GetNSObject<NSNumber> (ptr)!) {
    return (int) num.Int32Value;
  }
}, false)));
```
This code can be simplified to use a static group method. So that it
looks like:
```csharp
NativeHandle retvalarrtmp;
ret = ((retvalarrtmp = global::ObjCRuntime.Messaging.NativeHandle_objc_msgSend (this.Handle, Selector.GetHandle ("sourceSampleDataTrackIDs"))) == IntPtr.Zero ? null! : (NSArray.ArrayFromHandleFunc <int> (retvalarrtmp, NSNumber.ToInt32, false)));
```
A seasoned C# developer would mention that in C# 10 and under using
method groups (specially static ones) alocates more memory than using
lambdas (lambdas were cached, static methods were not, see
dotnet/roslyn#5835). Alas, this is not longer
the case after dotnet/roslyn#58288 which means
that the memory usage is the same allowing us to clean our generated
code.

Using static group methods also opens the door to other possible
improvements mentioned in the roslyn PR.

PS: This is some extra work we are doing to make the generated code
simpler before we move to rgen.

---------

Co-authored-by: GitHub Actions Autoformatter <github-actions-autoformatter@xamarin.com>
Co-authored-by: Rolf Bjarne Kvinge <rolf@xamarin.com>