Make a way to suppress MA0003 (#3)

I add a test to allow:

    new UITextField().EditingDidBegin += _proxy.OnEditingDidBegin;

    // This should warn, because it is NSObject
    class UITextFieldProxy : NSObject
    {
        // But then we suppressed the warning
        [UnconditionalSuppressMessage("Memory", "MA0003")]
        public void OnEditingDidBegin(object sender, EventArgs e) { }
    }

I added code to look up the attribute on the method from this statement:

    new UITextField().EditingDidBegin += _proxy.OnEditingDidBegin;

This also uncovered a bug in the analyzer:

    --if (attribute.AttributeClass.ContainingNamespace.Name != "System.Diagnostics.CodeAnalysis")
    ++if (attribute.AttributeClass.ContainingNamespace.ToString() != "System.Diagnostics.CodeAnalysis")

In this example `Name` was just `"CodeAnalysis"`. I have no idea why,
but using `.ToString()` instead was successful. All tests pass with this
change, so I'm going with it.

MemoryAnalyzers/MemoryAnalyzers.Test/MemoryAnalyzersUnitTests.cs

@@ -558,7 +558,7 @@ class MyView : UIView
 
 					public MyView()
 					{
-						new UITextField().EditingDidBegin += _proxy.{|#0:OnEditingDidBegin|};;
+						new UITextField().EditingDidBegin += _proxy.{|#0:OnEditingDidBegin|};
 					}
 
 					// This should warn, because it is NSObject
@@ -572,5 +572,39 @@ class UITextFieldProxy : NSObject
 			var expected = VerifyCS.Diagnostic("MA0003").WithLocation(0).WithArguments("OnEditingDidBegin");
 			await VerifyCS.VerifyAnalyzerAsync(test, expected);
 		}
+
+		[TestMethod]
+		public async Task SubscriptionForProxyClass_Suppressed()
+		{
+			var test = """
+				[Register(Name = "UITextField", IsWrapper = true)]
+				class UITextField
+				{
+					[UnconditionalSuppressMessage("Memory", "MA0001")]
+					public event EventHandler EditingDidBegin;
+				}
+
+				class MyView : UIView
+				{
+					[UnconditionalSuppressMessage("Memory", "MA0002")]
+					readonly UITextFieldProxy _proxy = new();
+
+					public MyView()
+					{
+						new UITextField().EditingDidBegin += _proxy.OnEditingDidBegin;
+					}
+
+					// This should warn, because it is NSObject
+					class UITextFieldProxy : NSObject
+					{
+						// But then we suppressed the warning
+						[UnconditionalSuppressMessage("Memory", "MA0003")]
+						public void OnEditingDidBegin(object sender, EventArgs e) { }
+					}
+				}
+			""";
+
+			await VerifyCS.VerifyAnalyzerAsync(test);
+		}
 	}
 }

MemoryAnalyzers/MemoryAnalyzers/MemoryAnalyzer.cs

@@ -178,6 +178,8 @@ static void AnalyzeSubscription(SyntaxNodeAnalysisContext context)
 			var rightInfo = context.SemanticModel.GetSymbolInfo(assignment.Right);
 			if (rightInfo.Symbol is not IMethodSymbol methodSymbol || methodSymbol.IsStatic)
 				return; // static methods are fine
+			if (HasUnconditionalSuppressMessage(methodSymbol, MA0003))
+				return; // Method has [UnconditionalSuppressMessage]
 			if (!IsNSObjectSubclass(methodSymbol.ContainingType))
 				return; // If the method is on a non-NSObject subclass, it's fine
 
@@ -203,7 +205,7 @@ static bool HasUnconditionalSuppressMessage(ISymbol symbol, string expectedCode)
 			{
 				if (attribute.AttributeClass is null)
 					continue;
-				if (attribute.AttributeClass.ContainingNamespace.Name != "System.Diagnostics.CodeAnalysis")
+				if (attribute.AttributeClass.ContainingNamespace.ToString() != "System.Diagnostics.CodeAnalysis")
 					continue;
 				if (attribute.AttributeClass.Name != "UnconditionalSuppressMessageAttribute")
 					continue;