feature request: Parser playground

I sometimes report issues related latest `babel/parser`. When I report, I use the local babel repository to reproduce problems. That's because there is no way to see the latest `@babel/parser` behavior on a browser(We cannot use **lastest** version on https://astexplorer.net/.

It is useful to have an official `@babel/parser` playground, like https://babeljs.io/repl.

Start by reviewing the existing Babel website and the referenced Babel REPL and AST Explorer workflows. Define how an official browser playground should expose the latest @babel/parser behavior, then verify that users can reproduce parser issues there.

Written by the indexing model from the issue text.