refactor(v2): i18n cleanups / refactors (#4405)

* chore: fix various intl stuff
- remove intl-locales-supported & intl since they're deprecated and only
needed for IE11
- add new polyfills for node 12
- clean up babel intl extractor
- reset jest test timezone to UTC so it passes even for East Coast
contributor

* chore: change build to include Node 14

* docs: update i18n reqs

jest.config.js

@@ -39,7 +39,7 @@ module.exports = {
   transform: {
     '^.+\\.[jt]sx?$': 'babel-jest',
   },
-  setupFiles: ['./jest/stylelint-rule-test.js'],
+  setupFiles: ['./jest/stylelint-rule-test.js', './jest/polyfills.js'],
   moduleNameMapper: {
     '@docusaurus/router': 'react-router-dom',
   },