feat(server/portforward): change route from /v1/openvpn/portforwarded to /v1/portforward

- This route has nothing to do with openvpn specifically
- Remove the `ed` in `portforwarded` to accomodate future routes such as changing the state of port forwarding
- maintaining retrocompatibility with `/v1/openvpn/portforwarded`
- maintaining retrocompatibility with `/openvpn/portforwarded`
- Moved to its own handler `/v1/portforward` instead of `/v1/vpn/portforward` to reduce the complexity of the vpn handler

internal/server/handlerv0.go

@@ -52,7 +52,7 @@ func (h *handlerV0) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			h.logger.Warn(err.Error())
 		}
 	case "/openvpn/portforwarded":
-		http.Redirect(w, r, "/v1/openvpn/portforwarded", http.StatusPermanentRedirect)
+		http.Redirect(w, r, "/v1/portforward", http.StatusPermanentRedirect)
 	case "/openvpn/settings":
 		http.Redirect(w, r, "/v1/openvpn/settings", http.StatusPermanentRedirect)
 	case "/updater/restart":