Converts this repository into a monorepo, containing the following npm packages:

   * agent-base
   * data-uri-to-buffer
   * degenerator
   * get-uri
   * https-proxy-agent
   * http-proxy-agent
   * pac-proxy-agent
   * pac-resolver
   * proxy
   * proxy-agent
   * socks-proxy-agent

Why? Mainly for ease of maintenance. It's difficult to monitor 10+ repositories and
keep their configurations in sync. Additionally:

   * Uses Turborepo
   * All packages have been converted to TypeScript
   * Common issue tracker for all related packages
   * Common eslint configuration
   * Shared GH Actions setup
   * Test changes for sub-packages against dependent parent packages

Runs a simple end to end test against NordVPN servers,
for `https-proxy-agent` and `socks-proxy-agent`.

Enable Vercel deployments to upload tarballs of each package,
so that they can be installed and tested before being released
in a mainline npm package release.

For example:

```
npm i https://proxy-agents-git-pack-tootallnate.vercel.app/proxy-agent.tgz
```

Windows tests seem to be tight at 2 minutes.

Using Build Command override in project settings instead.

ncc v0.24.0 has an issue parsing "lru-cache@9" :/

```
ncc: Version 0.24.0
ncc: Compiling file index.js
ncc: Using typescript@4.9.5 (local user-provided)
Error: Module parse failed: Unexpected token (27:15)
File was processed with these loaders:
 * ../../node_modules/.pnpm/@vercel+ncc@0.24.0/node_modules/@vercel/ncc/dist/ncc/loaders/empty-loader.js
 * ../../node_modules/.pnpm/@vercel+ncc@0.24.0/node_modules/@vercel/ncc/dist/ncc/loaders/relocate-loader.js
 * ../../node_modules/.pnpm/@vercel+ncc@0.24.0/node_modules/@vercel/ncc/dist/ncc/loaders/shebang-loader.js
You may need an additional loader to handle the result of these loaders.
|     //@ts-ignore
|     AS = class AbortSignal {
>         onabort;
|         _onabort = [];
|         reason;
```

Closes #142.

…on request options (#148)

Enables `keepAlive: true` option for all proxy agent classes.
When set, the `Proxy-Connection: Keep-Alive` HTTP header
will be sent to HTTP proxies.

Also remove "bugs" and "homepage" since they're redundant

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>