PCHR-4049: Upgrade gulp

[igorpavlov-zz]

Overview

This PR is upgrading Gulp to the version 4.0.

Technical Details

Basic changes

Please refer to compucorp/civihr#2804 to see the basic technical details that were also applied in this PR.

Compass

If Compass or/and Compass-Bootstrap is not yet installed on the computer gulp will not show any error and the css file will not be updated. To prevent this an error is now shown:

// The app style relies on compass's gems,
// so we need to rely on it for the time being
exec('compass compile', function (error, stdout) {
  if (error) {
    console.log(error);

---

✅Gulp tested (deleted dist files and successfully rebuilt without changes)
✅Requirejs tested
✅Test tested
✅Sass tested
✅Watch tested

[AkA84]

these are still dev dependencies, not dependencies

[igorpavlov-zz]

Nice catch, my bad, I seem to have installed without --save-dev flag.