async copyApplication () {
    await super.copyApplication()
    if (this.options.iconNuget) {
      const iconNuget = path.join(this.stagingAppDir, this.options.iconNugetName)
      await super.copyIcon(this.options.iconNuget, iconNuget)
    }
    return this.copySquirrelUpdater()
  }
Copy the application into the package.