refactor: use es6 class

[ShukantPal]

Resolves #905

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@5cf38cf). Click here to learn what that means.
The diff coverage is 57.69%.

@@            Coverage Diff            @@
##             master     #911   +/-   ##
=========================================
  Coverage          ?   65.28%           
=========================================
  Files             ?       21           
  Lines             ?     1815           
  Branches          ?        0           
=========================================
  Hits              ?     1185           
  Misses            ?      630           
  Partials          ?        0

Impacted Files	Coverage Δ
bin/templates/cordova/lib/retry.js	100% <ø> (ø)
bin/templates/cordova/lib/android_sdk.js	100% <ø> (ø)
bin/templates/cordova/lib/emulator.js	89.83% <100%> (ø)
...lates/cordova/lib/config/GradlePropertiesParser.js	76.66% <100%> (ø)
bin/templates/cordova/lib/build.js	31.61% <12.5%> (ø)
bin/templates/cordova/lib/utils.js	17.85% <17.85%> (ø)
bin/templates/cordova/lib/check_reqs.js	51.2% <25%> (ø)
bin/templates/cordova/lib/prepare.js	34.53% <37.5%> (ø)
...n/templates/cordova/lib/builders/ProjectBuilder.js	71.97% <39.53%> (ø)
bin/lib/utils.js	75% <75%> (ø)
... and 2 more

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[breautek]

Please edit the PR to use the github keyword syntax for linking PRs to issues.

https://help.github.com/en/github/managing-your-work-on-github/closing-issues-using-keywords

e.g: "Fixes #905"

[erisu]

I skimmed though it and most looked OK.
I think there was one change that was not correct. Please confirm.