Changes:
- Migrate to TypeScript. `react-intl` natively supports TypeScript now.
- Upgrade corresponding `formatjs` packages.
- Dynamically polyfill Intl API per locale since those polyfills are huge.
- Migrate to recommended workflow per https://formatjs.io/docs/getting-started/application-workflow
* Update dependencies
> Update dependencies
* Changes to make v3 work
> Use hook `useIntl` instead of HOC `injectIntl`
> Change use of class components
> Changes to dependencies
* Small changes
Small changes
* Run prettier over packages/**/*.js
* Run prettier over packages/**/*.ts
* Run prettier over examples
* Remove tslint
* Run prettier over examples
* Run prettier over all markdown files
* Run prettier over json files
