Feat/download file puppeteer

[kobenguyent]

• Introduce download action for puppeteer.
• test is added.

[DavertMik]

Thanks, a very nice PR but it needs some improvement.
I don't see right now how to use this method.
Let's assume I download a file and I want to check it somehow. Can you give me an example how would you do some testing using file download?
Maybe we will need to use Filesystem helper to fulfil the scenario?

[kobenguyent]

This is basically to click a button, link in AUT to download file. This file is downloaded to output folder. And this function makes sure download function is working on the application.

For instance: you have a web application that let users can upload/ download their images, documents. By using I.downloadFile('locator'), if file is downloaded to output folder, then downloading function is working. Moreover, after file is downloaded, we can do further check with downloaded file if we want, like parsing the pdf and checking contents, etc.

Hope I explain it’s clear ^^

[DavertMik]

Sorry, I had this review as a draft for I think a month now. Unfortunately only now I found out it was not submitted :(

[DavertMik]

request-promise is outdated. Let's switch to axios

[kobenguyent]

I created another PR to follow up this -> #1542