[Feature Request] Add sample for using `Buffer` polyfills

Describe the solution you'd like

Add a sample that demonstrate how to add support for using the Buffer class from sandboxed code, by loading an appropriate polyfill through a custom Webpack configuration.

Context

Some users have expressed their need for using the Buffer class in code that runs inside the Workflow sandbox. After discussion, however, our team has determined that it's preferable not to provide out-of-the-box support for that module, since that goes against some of our mid-term and long-term objectives, notably regarding the possibly of supporting other JavaScript runtimes (eg. Deno, browser, etc). Users may easily work around missing APIs by loading appropriate polyfills from their Webpack bundler.

Start by locating the existing TypeScript samples and the custom Webpack configuration used for sandboxed Workflow code. Add a sample showing how to load a Buffer polyfill through that configuration and use Buffer from sandboxed code; done means the sample clearly demonstrates the workaround.