[bgen] Handle in-process warning differences

Treat the .NET and NUnit OverloadResolutionPriorityAttribute definitions as an expected polyfill collision while preserving the attribute for generated bindings. Account for intentional binding-test diagnostics now surfaced through the in-process MSBuild logger.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 0de016bf-f41d-4d46-aab1-34c9850c8f4b

Author: rolfbjarne

src/bgen/AttributeManager.cs

@@ -19,6 +19,7 @@ public class AttributeManager {
 		"System.Runtime.CompilerServices.NullableContextAttribute",
 		"System.Runtime.CompilerServices.NativeIntegerAttribute",
 		"System.Diagnostics.CodeAnalysis.DynamicDependencyAttribute",
+		"System.Runtime.CompilerServices.OverloadResolutionPriorityAttribute",
 	};
 
 	// Cache raw GetCustomAttributesData() results per provider to avoid repeated reflection allocations.

tests/dotnet/UnitTests/ProjectTest.cs

@@ -3050,6 +3050,10 @@ public void PublishAotMonoTouchTest_NoIL2009 (ApplePlatform platform, string run
 								.FilterWarnings (platform);
 			var expectedWarnings = new ExpectedBuildMessage [] {
 				new ExpectedBuildMessage ($"ILC", $"MonoTouchFixtures.ObjCRuntime.ClassTest.GetHandle(): Using member 'System.Type.MakeArrayType()' which has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. The code for an array of the specified type might not be available."),
+				new ExpectedBuildMessage ($"MSBuild", $"The type Bindings.Test.Protocol.P2 has a [Protocol] and a [BaseType] attribute, but no [Model] attribute. This is likely incorrect; either remove the [BaseType] attribute, or add a [Model] attribute."),
+				new ExpectedBuildMessage ($"MSBuild", $"The type Bindings.Test.ProtocolWithBlockProperties has a [Protocol] and a [BaseType] attribute, but no [Model] attribute. This is likely incorrect; either remove the [BaseType] attribute, or add a [Model] attribute."),
+				new ExpectedBuildMessage ($"MSBuild", $"[NullAllowed] should not be used on methods, like 'Element GetElement(Key)', but only on properties, parameters and return values."),
+				new ExpectedBuildMessage ($"MSBuild", $"[NullAllowed] should not be used on methods, like 'Foundation.NSEnumerator`1[Element] GetEnumerator()', but only on properties, parameters and return values."),
 				new ExpectedBuildMessage ($"MSBuild", $"It's not safe to remove the dynamic registrar, because monotouchtest references 'ObjCRuntime.Runtime.ConnectMethod (System.Reflection.MethodInfo, ObjCRuntime.Selector)'."),
 				new ExpectedBuildMessage ($"MSBuild", $"It's not safe to remove the dynamic registrar, because monotouchtest references 'ObjCRuntime.Runtime.ConnectMethod (System.Type, System.Reflection.MethodInfo, Foundation.ExportAttribute)'."),
 				new ExpectedBuildMessage ($"MSBuild", $"It's not safe to remove the dynamic registrar, because monotouchtest references 'ObjCRuntime.Runtime.ConnectMethod (System.Type, System.Reflection.MethodInfo, ObjCRuntime.Selector)'."),