Add "enum cloning" source generator

generators/Dalamud.EnumGenerator/Dalamud.EnumGenerator.Tests/Utils/TestAdditionalFile.cs

@@ -0,0 +1,21 @@
+using System.Threading;
+
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Text;
+
+namespace Dalamud.EnumGenerator.Tests.Utils;
+
+public class TestAdditionalFile : AdditionalText
+{
+    private readonly SourceText text;
+
+    public TestAdditionalFile(string path, string text)
+    {
+        Path = path;
+        this.text = SourceText.From(text);
+    }
+
+    public override SourceText GetText(CancellationToken cancellationToken = new()) => this.text;
+
+    public override string Path { get; }
+}