Use git binary for fetch to make ssh easier

[amisevsk]

What does this PR do?

Make changes necessary to make basic SSH support work in the project clone container (basically, just use git binary for all operations involving remote repos.

Currently, project-clone expects ssh keys to be stored in /.ssh, since no $HOME directory is configured for that container. To ensure compatibility with other editors, we should refine how users/homedirs are defined to make sure the same secret can be used for all workspace containers.

What issues does this PR fix or reference?

Closes #400

Is it tested? How?

Can be tested using the image quay.io/amisevsk/project-clone:ssh (change RELATED_IMAGE_project_clone on the controller deployment).

To manually test usage with a private repo, create a new ssh key (without passkey) and upload the pubkey to GitHub. Then, create a k8s secret in your namespace:

cat > /tmp/gitconfig <<EOF
host *
  IdentityFile /.ssh/id_rsa
  StrictHostKeyChecking = no
EOF

kubectl create secret generic git-ssh-key \
  --from-file=id_rsa=/path/to/private-key \
  --from-file=id_rsa.pub=/path/to/public-key \
  --from-file=config=/tmp/gitconfig

kubectl patch secret git-ssh-key --type merge -p \
  '{"metadata": {
     "labels": {
        "controller.devfile.io/mount-to-devworkspace": "true"
      }, 
      "annotations": {
        "controller.devfile.io/mount-path": "/.ssh/"
      }
    }
  }'

Once this is done, you should be able to create DevWorkspaces that use private repos.

PR Checklist

• E2E tests pass (when PR is ready, comment /test v7-devworkspaces-operator-e2e, v7-devworkspace-happy-path to trigger)
  • v7-devworkspaces-operator-e2e: DevWorkspace e2e test
  • v7-devworkspace-happy-path: DevWorkspace e2e test

[sleshchenko]

During testing I noticed that the following message happens twice, on cloning and fetching

Failed to add the host to the list of known hosts (/.ssh/known_hosts).

But it's not really related to this PR changes.
I think ssh config just needs to be fixed to specify writable known_host

[sleshchenko]

/test v7-devworkspaces-operator-e2e, v7-devworkspace-happy-path

[sleshchenko]

rebased against main branch to fix required PR checks

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: amisevsk, JPinkney, sleshchenko

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