C#: Suppress EventHandler suffix diagnostic for signals

Suppress CA1711 for signal delegates because they are used in events so
the naming follows the guidelines.

modules/mono/editor/Godot.NET.Sdk/Godot.SourceGenerators/EventHandlerSuffixSuppressor.cs

@@ -0,0 +1,53 @@
+using System.Collections.Immutable;
+using System.Linq;
+using System.Threading;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace Godot.SourceGenerators
+{
+    [DiagnosticAnalyzer(LanguageNames.CSharp)]
+    public class EventHandlerSuffixSuppressor : DiagnosticSuppressor
+    {
+        private static readonly SuppressionDescriptor _descriptor = new(
+            id: "GDSP0001",
+            suppressedDiagnosticId: "CA1711",
+            justification: "Signal delegates are used in events so the naming follows the guidelines.");
+
+        public override ImmutableArray<SuppressionDescriptor> SupportedSuppressions =>
+            ImmutableArray.Create(_descriptor);
+
+        public override void ReportSuppressions(SuppressionAnalysisContext context)
+        {
+            foreach (var diagnostic in context.ReportedDiagnostics)
+            {
+                AnalyzeDiagnostic(context, diagnostic, context.CancellationToken);
+            }
+        }
+
+        private static void AnalyzeDiagnostic(SuppressionAnalysisContext context, Diagnostic diagnostic, CancellationToken cancellationToken = default)
+        {
+            var location = diagnostic.Location;
+            var root = location.SourceTree?.GetRoot(cancellationToken);
+            var dds = root?
+                .FindNode(location.SourceSpan)
+                .DescendantNodesAndSelf()
+                .OfType<DelegateDeclarationSyntax>()
+                .FirstOrDefault();
+
+            if (dds == null)
+                return;
+
+            var semanticModel = context.GetSemanticModel(dds.SyntaxTree);
+            var delegateSymbol = semanticModel.GetDeclaredSymbol(dds, cancellationToken);
+            if (delegateSymbol == null)
+                return;
+
+            if (delegateSymbol.GetAttributes().Any(a => a.AttributeClass?.IsGodotSignalAttribute() ?? false))
+            {
+                context.ReportSuppression(Suppression.Create(_descriptor, diagnostic));
+            }
+        }
+    }
+}