fix(http): Set host header based on in

fix https://github.com/fosrl/pangolin/issues/2952 issue by setting the incoming host header to the outgoing one by the reverse proxy, this was the default behaviour when using single proxy but now since we use more features it now rewrites the host header

netstack2/http_handler.go

@@ -291,6 +291,9 @@ func (h *HTTPHandler) getProxy(target HTTPTarget) *httputil.ReverseProxy {
 	proxy := &httputil.ReverseProxy{
 		Rewrite: func(pr *httputil.ProxyRequest) {
 			pr.SetURL(targetURL)
+			if host := pr.In.Host; host != "" {
+				pr.Out.Host = host
+			}
 			// SetXForwarded sets X-Forwarded-For from the inbound request's
 			// RemoteAddr (the WireGuard/netstack client address), along with
 			// X-Forwarded-Host and X-Forwarded-Proto. Using Rewrite instead of