fix: add Host header when used with http_proxy

[magicdawn]

fix: add Host header when used with http_proxy

What kind of change does this PR introduce?
a bugfix

Did you add tests for your changes?

If relevant, did you update the documentation?

Summary

Does this PR introduce a breaking change?
no

Other information

manual http.get() differs from use a agent = HttpProxyAgent() (imported from http-proxy-agent package) instance, for Host header.

say proxy for https://httpbin.org/headers

• use https.get('https://httpbin.org/headers', { agent: HttpProxyAgent('http://127.0.0.1:54321') }) will have Host: httpbin.org sent to 127.0.0.1:54321
• https.get without Host set will use proxy's host 127.0.0.1:54321 which breaks my current proxy server.

I found some evidence indicates it's client's job to make it right.

• https://datatracker.ietf.org/doc/html/rfc2616#section-14.23
• from http: the definitive guide Book, page 419

If the URL contains a hostname, the Host header must contain the same name.

Host headers and proxies
Some browser versions send incorrect Host headers, especially when configured to use proxies. > For example, when configured to use a proxy, some older versions of Apple and PointCast clients mistakenly sent the name of the proxy instead of the ori- gin server in the Host header.

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AND why https-proxy-agent but not http-proxy-agent?

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[OrKoN]

Hey thanks for the PR. Would you mind signing the CLA agreement?

AND why https-proxy-agent but not http-proxy-agent?

That is lost to history :)

[magicdawn]

signed.