Tezt/Cloud: adds a new mode to enable the new ssh deployment

on top of !17928 (merged)

This is the first testable MR.

How to test

Prerequisites

• a machine on debian bookworm which you can connect with the root user with ssh public key authentication given its ip address
• docker must be installed (package docker.io)
• the docker image must be present in the local docker

Run the scenario using the ssh reachable machine

In this example, the prepared machine can be reached at 35.205.84.119

dune exec tezt/tests/cloud/main.exe -- DAL --bootstrap -v --prometheus --dockerfile-alias baugr --tezt-cloud baugr4 --log-file /tmp/log --refresh-binaries --vms-limit 0 --proxy --proxy-localhost --ssh-host 35.205.84.119