Two workflows have been added,
* PHP build - Runs tests on version 7.2, 7.3, also runs phpcs
* Node.js build - Runs tests on version 8.x, 10.x, 12.x, also
runs ESLint
Bug: T218639
Additional changes in this PR include,
* Added composer.json
* Refactored the folder structure.
* Added editorconfig.
* Added PHPCS and formatted existing code.
* Changes to use a single license - GPL-2.0-or-later
* ESLint related fixes
Bug: T218639