Test Runner: Add support for additional nunit args. (#775)

NWN.Anvil.TestRunner/src/main/TestRunnerService.cs

@@ -25,6 +25,8 @@ internal sealed class TestRunnerService
     private readonly Queue<Assembly> testAssemblyQueue = new Queue<Assembly>();
     private readonly string outputDir;
 
+    private readonly string additionalArgs = Environment.GetEnvironmentVariable("ANVIL_NUNIT_ARGS");
+
     private Thread testWorkerThread;
 
     public TestRunnerService(MainThreadSynchronizationContext mainThreadSynchronizationContext, PluginStorageService pluginStorageService)
@@ -78,7 +80,8 @@ private async void Shutdown()
     private string[] GetRunnerArguments(Assembly assembly)
     {
       string outputPath = Path.Combine(outputDir, assembly.GetName().Name!);
-      string args = $"--mainthread --work={outputPath}";
+
+      string args = $"--mainthread --work={outputPath} {additionalArgs}";
       return string.IsNullOrEmpty(args) ? Array.Empty<string>() : CommandLineParser.SplitCommandLineIntoArguments(args, false).ToArray();
     }
   }