Support packaging nativefier applications into Squirrel-based installers

[AdrianDC]

Squirrel is "an installation and update framework for Windows desktop apps ".

This PR adds electron-squirrel-startup, allowing to package nativefier applications
into squirrel-based setup installers. Squirrel require this entrypoint to perform
desktop and startup menu creations, without showing the UI on setup launches.

• References: https://github.com/mongodb-js/electron-squirrel-startup

• Resolves electron-winstaller and electron-installer-windows support of desktop / startup menu shortcuts for nativefier packaged applications.

• The electron-squirrel-startup entrypoint has no effect on both Linux and Darwin, only on Windows

• Supporting it directly inside nativefier avoids having to "hack" around the existing main.js
  and including dependencies from electron-squirrel-startup in an intermediate package
  to be included in a third layer for the final installer executable

• The following script based on both nativefier and electron-winstaller templates
  represents a portable proof of concept for this merge request :

var nativefier = require('nativefier').default;
var electronInstaller = require('electron-winstaller');

var options = {
  name: 'Web WhatsApp',
  targetUrl: 'http://web.whatsapp.com',
  platform: 'windows',
  arch: 'x64',
  version: '0.36.4',
  out: '.',
  overwrite: false,
  asar: false,
  counter: false,
  bounce: false,
  width: 1280,
  height: 800,
  showMenuBar: false,
  fastQuit: false,
  userAgent: 'Mozilla ...',
  ignoreCertificate: false,
  ignoreGpuBlacklist: false,
  enableEs3Apis: false,
  insecure: false,
  honest: false,
  zoom: 1.0,
  singleInstance: false,
  fileDownloadOptions: {
    saveAs: true
  },
  processEnvs: {
    GOOGLE_API_KEY: '<your-google-api-key>'
  }
};

nativefier(options, function(error, appPath) {
  if (error) {
    console.error(error);
    return;
  }
  console.log('App has been nativefied to', appPath);

  resultPromise = electronInstaller.createWindowsInstaller({
    appDirectory: 'Web WhatsApp-win32-x64',
    outputDirectory: './',
    authors: 'Web WhatsApp',
    exe: 'Web WhatsApp.exe'
  });

  resultPromise.then(() => console.log('It worked!'), e => console.log(`No dice: ${e.message}`));
});

[ronjouch]

@AdrianDC thanks for the PR! What is this? What does it have to do with Nativefier? A tiny bit of context, please 🙂.

[AdrianDC]

@AdrianDC thanks for the PR! What is this? What does it have to do with Nativefier? A tiny bit of context, please 🙂.

I completed the merge request's presentation with the last 4 items,
including a proof-of-concept to present a simple use case and validate the additions

[ronjouch]

@AdrianDC okay, got it, thanks for the explanation! Merging and adding docs.

[ronjouch]

@AdrianDC okay, got it, thanks for the explanation! Merging and adding docs.

That will do for now: https://github.com/jiahaog/nativefier/blob/master/docs/api.md#packaging-squirrel-based-installers . Thanks again @AdrianDC, and 🙏 for the delay. Merging a few other things over the weekend, then cutting a release.

[steveacalabro]

missing ../screen is still an issue for me @AdrianDC (Edit: Just needs to be released to a new version)