[CI/docker] remote / ssh support

[GuillaumeDua]

[UPDATE]

as a multi-stage image:

FROM cpp-toolchain-dev as ssh-support
# etc.

---

part of #196 , but as a separated container

---

• SSH remote connection
• vscode remote developpement (ssh, rsync)
• remote debug

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• shared network with the cpp-toolchain container ?

version: '3'
services:
  container1:
    image: sshtest
    build: .
    networks:
      - sshtest
    ports:
      - 2201:22

  container2:
    image: sshtest
    build: .
    networks:
      - sshtest
    ports:
      - 2202:22

networks:
  sshtest: