support `x-forwarded-host` for che-jwtproxy

[zWingz]

Is your enhancement related to a problem? Please describe

che-jwtproxy use req.host to make a redirect url. So If I have a new proxy-server, and proxy http to jwtproxy. https://my-proxy.com --> https://jwtproxy.com --> http://127.0.0.1:8080. so, che-jwtproxy with get jwtproxy.com from req.host, and redirect to jwtproxy.com, but I hope it can redirect to my-proxy.com.

Describe the solution you'd like

I would like to set header x-forwarded-host: my-proxy.com, and che-jwtproxy will redirect to my-proxy.com

Describe alternatives you've considered

No response

Additional context

https://github.com/eclipse-che/che-jwtproxy/blob/main/jwt/jwt.go#L187 https://github.com/eclipse-che/che-jwtproxy/blob/main/jwt/jwt.go#L73