feat(cli): add SSH support for renku session

[Panaetius]

closes #3289
closes #3290

Adds renku session setup-ssh command to configure SSH locally for access to a deployment (need to be logged in).
Adds renku session start --ssh command that setups of keys in the project for SSH access and configures the local machine for access to a session. Also perfirms setup-ssh if not done already.
Adds renku session open --ssh command that opens an SSH connection to a session.

[Panaetius]

Steps to test:

• Create a project there and set the base image in the Dockerfile to ARG RENKU_BASE_IMAGE=renku/renkulab-py:python-3.9.12-4d92ea3
• Clone the project locally
• Install renku on your local machine from this PR pip install git+https://github.com/SwissDataScienceCenter/renku-python.git@topic/3289-ssh-session-setup
• renku login renku-ci-nb-1389.dev.renku.ch
• renku session setup-ssh (optional, sets up SSH jump host and keys for the deployment). you can also use -k <path to private key> if you don't want a key generated for you and use an existing key instead
• export RENKU_IMAGE_REGISTRY="registry.dev.renku.ch" this is a workaround since renku session start doesn't currently work for external gitlab deployments where gitlab is not at gitlab. or /gitlab (which our CI deployments are). On dev or renkulab this wouldn't be necessary
• renku session start -p renkulab --ssh starts the session, adds your key to authorized_hosts(the first time) and prints the connection name
• Connect with VScode with the printed session name or renku session open --ssh <session id> for just a shell

[m-alisafaee]

Thanks Ralf! This is great! I couldn't create a project in the deployed env; it hangs when fetching templates.

[Panaetius]

I couldn't create a project in the deployed env; it hangs when fetching templates.
That weird. I guess you could always just create the project on Dev as well and it'd show up here.
Or maybe it'll work now that I'm redeploying it with the new commit?