feat(gateway): add iptables-legacy and temporary port redirection

- Install iptables-legacy package in Dockerfile to support iptables rules
- Add temporary iptables rules in set_gateway.sh to redirect HTTP/HTTPS traffic from wg0 to 172.18.103.2
- These rules are temporary and should be removed after service-exec go update

Dockerfile

@@ -10,7 +10,9 @@ FROM alpine:latest
 
 COPY --from=0 /root/.cargo/bin/boringtun-cli /usr/bin/boringtun
 
-RUN apk add --no-cache tini wireguard-tools \
+# replace the commented line with the following after service-exec go update
+#RUN apk add --no-cache tini wireguard-tools \
+RUN apk add --no-cache tini wireguard-tools iptables-legacy \
  && apk add --no-cache --virtual .build-deps libcap \
  && setcap cap_net_admin+ep /usr/bin/boringtun \
  && apk del --purge .build-deps \