function readText(resp, info):Promise<string> {
  switch (info.rnfbEncode) {
    case 'base64':
      return Promise.resolve(resp.text())
      break
    case 'path':
      return resp.text()
      break
    default:
      return Promise.resolve(resp.text())
      break
  }
}
Get response data as string.
@param  {FetchBlobResponse} resp Response data object from RNFB fetch call.
@param  {RNFetchBlobResponseInfo} info Response informations.
@return {Promise<string>}