fix: Remove a CA1062 in generated code

Author: davidkallesen

src/Atc.Rest.ApiGenerator.Framework.Minimal/ContentGenerators/ContentGeneratorServerWebApplicationExtensions.cs

@@ -39,6 +39,8 @@ public string Generate()
             sb.AppendLine(8, "this WebApplication app,");
             sb.AppendLine(8, "string applicationName)");
             sb.AppendLine(4, "{");
+            sb.AppendLine(8, "ArgumentNullException.ThrowIfNull(app);");
+            sb.AppendLine();
             sb.AppendLine(8, "if (!app.Environment.IsDevelopment())");
             sb.AppendLine(8, "{");
             sb.AppendLine(12, "return app;");