message: Feed VSCode diagnostic code to Roslyn diagnostic id
  Relates to
diff: @@ -335,6 +335,7 @@ class DiagnosticsProvider extends AbstractSupport {
  let message = `${quickFix.Text} [${quickFix.Projects.map(n => this._asProjectLabel(n)).join(', ')}]`;
  let diagnostic = new vscode.Diagnostic(toRange(quickFix), message, display.severity);
  + diagnostic.code = quickFix.Id;
  if (display.isFadeout) {
  diagnostic.tags = [vscode.DiagnosticTag.Unnecessary];
  