Add DiffPlex to source generator tests

Author: Genbox

Src/FastData.SourceGenerator.Tests/Properties/ModuleInitializer.cs

@@ -0,0 +1,10 @@
+using System.Runtime.CompilerServices;
+using VerifyTests.DiffPlex;
+
+namespace Genbox.FastData.Generator.CPlusPlus.Tests.Properties;
+
+internal static class ModuleInitializer
+{
+    [ModuleInitializer]
+    public static void Initialize() => VerifyDiffPlex.Initialize(OutputType.Compact);
+}