[SceneKit] Add support for Xcode 15 beta 6 (#18778)

Notes:
- Beta 6 changes are targeting only visionOS
- Adding an [Abstract] to an existing protocol is a breaking change so
added a conditional XAMCORE and added xtro error to .ignore

---------

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

src/scenekit.cs

@@ -3293,6 +3293,13 @@ interface SCNSceneRenderer {
 #endif
 		[Export ("currentRenderPassDescriptor")]
 		MTLRenderPassDescriptor CurrentRenderPassDescriptor { get; }
+
+		[Watch (10, 0), TV (17, 0), Mac (14, 0), iOS (17, 0), MacCatalyst (17, 0)]
+#if XAMCORE_5_0
+		[Abstract]
+#endif
+		[Export ("workingColorSpace")]
+		CGColorSpace WorkingColorSpace { get; }
 	}
 
 	[MacCatalyst (13, 1)]

tests/xtro-sharpie/api-annotations-dotnet/common-SceneKit.ignore

@@ -64,3 +64,6 @@
 
 # normal pattern accept null delegate and unit tests shows it works just fine
 !extra-null-allowed! 'System.Void SceneKit.SCNAvoidOccluderConstraint::set_Delegate(SceneKit.ISCNAvoidOccluderConstraintDelegate)' has a extraneous [NullAllowed] on parameter #0
+
+## we cannot add abstract members to existing SCNSceneRenderer protocols (breaking changes)
+!incorrect-protocol-member! SCNSceneRenderer::workingColorSpace is REQUIRED and should be abstract

tests/xtro-sharpie/common-SceneKit.ignore

@@ -18,6 +18,7 @@
 !incorrect-protocol-member! SCNSceneRenderer::setTemporalAntialiasingEnabled: is REQUIRED and should be abstract
 !incorrect-protocol-member! SCNSceneRenderer::setUsesReverseZ: is REQUIRED and should be abstract
 !incorrect-protocol-member! SCNSceneRenderer::usesReverseZ is REQUIRED and should be abstract
+!incorrect-protocol-member! SCNSceneRenderer::workingColorSpace is REQUIRED and should be abstract
 
 ## same for SCNActionable, it is required member of a protocol added to .NET
 !incorrect-protocol-member! SCNActionable::actionKeys is REQUIRED and should be abstract