fix: adding Host header value validation on proxy

[jkyberneees]

This PR fixes/add first level of validation to the Host header value. Without this check, the proxy would throw an internal error if the Host header is missing.

A Host header field must be sent in all HTTP/1.1 request messages. A 400 (Bad Request) status code may be sent to any HTTP/1.1 request message that lacks a Host header field or that contains more than one.

Checklist

• [x] run npm run test and npm run benchmark
• [x] tests and/or benchmarks are included
• [x] documentation is changed or added
• [x] commit message and code follows the Developer's Certification of Origin and the Code of conduct

[jkyberneees]

cc @osvaldo2627

[Eomm]

Any update on this?