code: function authorized (req, res) {
    const { params, uppy } = req
    const providerName = params.providerName
  
    if (!uppy.providerTokens || !uppy.providerTokens[providerName]) {
      return res.json({ authenticated: false })
    }
  
    const token = uppy.providerTokens[providerName]
    uppy.provider.list({ token, uppy }, (err, response, body) => {
      const notAuthenticated = Boolean(err)
      if (notAuthenticated) {
        logger.debug(`${providerName} failed authorizarion test err:${err}`, 'provider.auth.check')
      }
      return res.json({ authenticated: !notAuthenticated })
    })
  }
docs: checks if companion is authorized to access a user's provider account.
  
  @param {object} req
  @param {object} res