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/middlewares/auth/middleware.go

@@ -37,6 +37,7 @@ func New(settings Settings, debugLogger DebugLogger) (
 				http.MethodGet + " /v1/updater/status": {},
 				http.MethodPut + " /v1/updater/status": {},
 				http.MethodGet + " /v1/publicip/ip":    {},
+				http.MethodGet + " /v1/portforward":    {},
 			},
 			logger: debugLogger,
 		}