Issue #3444587 by alexpott: Add CSS to prettier command and fix core/misc/jquery.form.js to be ignored

Issue #3278415 by nod_, lauriii, catch, Wim Leers, longwave, xjm, claudiu.cristea: Remove usages of the JavaScript ES6 build step, the build step itself, and associated dev dependencies

Issue #2591827 by longwave, neclimdul, elachlan, daffie: Add YAML linting to core coding standards checks

Issue #2981652 by ApacheEx, corbacho, drpal, dawehner, xjm, alexpott, lauriii: Format core JavaScript using recently add Prettier