socks5 support for proxying requests

[catdevnull]

describe the feature you'd like to see

hi! cobalt currently supports http/s proxies through undici's ProxyAgent. unfortunately, undici's ProxyAgent doesn't support socks4/5 proxies, which are useful as sometimes http/s proxies aren't available.

is there interest in implementing socks4/5 proxies, like with fetch-socks? it should be fairly straight forward (check if API_EXTERNAL_PROXY is a socks4/5 proxy, if yes, create the dispatcher using fetch-socks)

thanks!

additional context

No response

[catdevnull]

i don't actually need this anymore but maybe still would be cool