[proxy-agent] Support for `getProxyForUrl` option

[mceIdo]

This is a recreation of this PR from the original repo. This PR adds the option to provide a getProxyForUrl(url: string) => string function as an option to the ProxyAgent constructor. We found it useful in places where proxy address is different for different hosts (and pac is not an option).

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: 00e6b0bd28cb2f2bd7d74f93c218bd285abbac7c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

| Name | Type | | ----------- | ----- | | proxy-agent | Minor |

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[vercel[bot]]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Updated (UTC)
proxy-agents	✅ Ready (Inspect)	Visit Preview	May 9, 2023 8:50am

[mceIdo]

Cool, changes are done - I did see the E2E test failed due to NORDVPN_USERNAME env var missing - is this something I'm missing?

[TooTallNate]

No you're not missing anything. GitHub Secrets aren't exposed to 3rd party pull requests, so I've disabled the E2E tests here: https://github.com/TooTallNate/proxy-agents/commit/f173f80dd50ed18375925713ccf9a6fcda95b1b1

[mceIdo]

Great, thanks :)