[NET-738] Do not try to resolve ip of remote address for passive mode if the FTP Server running behind a Proxy.

[precoder]

Hello,

As we described in the ticket, FTP Client tries to resolve the IP address of the remove host for the Passive Connection.
However this attempt can never work if the FTP Server is running behind a proxy outside of the network, therefore if there is a Proxy Configured in between, it is better to rely on the address delivered by the Server.

I created a docker enviroment to test this by putting the FTP Server and PROXY into one docker network such as ftp-server-network and our client with PROXY in another network such as ftp-client-network.
After the fix client could list the files from the FTP Server behind the proxy.

[precoder]

A docker compose setup that I used for testing briefly looks like this:

version: "3.3"
services:
  ftpclient:
    image: <your-ftp-client-with-commos-net>:latest
    networks:
      ftp-client-network:
        aliases:
          - ftpclient.ftpclient.internal
  ftpserver:
    image: <your-ftp-server>:latest
    restart: always
    networks:
      ftp-server-network :
        aliases:
          - ftp.ftp.internal
    ports:
      - 21:21
  proxy:
    image: <your-http-proxy-such-as-squidproxy>:latest
    restart: always
    networks:
      ftp-client-network:
        aliases:
          - proxy.ftpclient.internal
      ftp-server-network :
        aliases:
          - proxy.ftp.internal
    ports:
      - 3128:3128

networks:
  ftp-client-network:
  ftp-server-network: