Adds a multi-file TSServer abstraction to the bug workbench

[orta]

This PR introduces a new package to the monorepo, as well as some infra for using esbuild instead of TSC for some of the playground packages.

The goal of this PR is to provide an editing experience for multi-file Playground samples. We already have "support" for Twoslash's // @filename: abc.ts in the bug-workbench, and now we have tooling support to back that up.

The tooling is based on microsoft/monaco-typescript#65 which lets you override the class that Monaco TypeScript interacts with the TSServer in. My subclass creates an additional vfs layer on top of the existing vfs layer used by MonacoTS which switches out the files which TypeScript sees in comparison to the model file which Monaco keeps track of.

What this screenshot shows:

• The bug workbench which is a less-used fork of the playground which we can safely test these changes out
• An extra // @filename: input.tsx is a decorator to help folks know what the 'default' file is.
• Auto-complete working inside app.ts inside this file
• Consolidated error messages across many files

[github-actions]

Got false positives?

Make changes to the global settings spellcheck.json in /microsoft/TypeScript-Website.

Make changes to this repo's settings in spellcheck.json.

Typos for README.md

Line	Typo
3	This is a WebWorker function which the Playground
3	how this works in this PR to monaco-typescript: https://github.com/microsoft
5	ch returns a subclass for the TSServer to monaco language bindings,

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