`Host` headers are not forwarded

[mimikwang]

Describe the bug
When using the forwardHeaders, the Host header is not forwarded.

To Reproduce
Steps to reproduce the behavior:

1. Add Host to the list of headers to be forwarded from the UI
2. Check the forwarded headers to see that it is missing

Expected behavior
Should forward the Host header

Desktop (please complete the following information):

• OS: MacOS
• Browser FireFox
• Version 145.0.2 (aarch64)

Additional context
This is likely because golang puts this into the request.Host field. From the doc

For incoming requests, the Host header is promoted to the Request.Host field and removed from the Header map.