message: genMonorepoPackageJson should generate package.json marked private
diff: @@ -111,6 +111,7 @@ async function generateMonoRepoPackageLockJson(monoRepo: MonoRepo, repoPackageJs
  interface PackageJson {
  name: string;
  version: string;
  + private?: boolean;
  dependencies: { [key: string]: string };
  devDependencies: { [key: string]: string };
  }
  @@ -156,6 +157,7 @@ async function generateMonoRepoInstallPackageJson(monoRepo: MonoRepo) {
  const repoPackageJson: PackageJson = {
  name: `@fluid-internal/${MonoRepoKind[monoRepo.kind].toLowerCase()}`,
  version: monoRepo.version,
  + private: true,
  dependencies: {},
  devDependencies: {},
  };
  