Proxy support

[axel3rd]

Using docsify-to-pdf-converter behind a (company) proxy could be a little tricky, mainly due to puppeteer:

1. For chromium package download via NPM
2. For configuring proxy & authentication for puppeteer rendering (some resource like https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js are required)

---

About [1], you should proxify https://storage.googleapis.com remote endpoint (with Nexus, Artifactory, ...) and configure puppeteer host download with you internal endpoint:

npm config set puppeteer_download_host http://repo.company.com/google-storage-remote

This item could perhaps be mentionned into readme.md

---

About [2], it requires feature development in render.js with new configuration options:

proxyHost: "proxy.company.com:8080", // Optional company proxy host
proxyUser: "foo", // Optional user for proxy authentication
proxyPassword: "bar", // Optional password for proxy user

When setted, these options should be used as below (details in #2234) ;

• proxy host:

docsify-to-pdf-converter/src/render.js

Lines 14 to 19 in aae1db4

	const browser = await puppeteer.launch({
	defaultViewport: {
	width: 1200,
	height: 1000,
	},
	});

==>

 const browser = await puppeteer.launch({ 
   defaultViewport: { 
     width: 1200, 
     height: 1000, 
   },
   args: [ '--proxy-server=proxy.company.com:8080' ]
 }); 

• proxy authentication:

docsify-to-pdf-converter/src/render.js

Lines 24 to 25 in 0569a0a

	const page = await browser.newPage();
	await page.goto(docsifyUrl, { waitUntil: "networkidle0" });

==>

 const page = await browser.newPage(); 
 await page.authenticate({
      username: 'foo',
      password: 'bar'
  });
 await page.goto(docsifyUrl, { waitUntil: "networkidle0" });