Add OCluster to development docker

[art-w]

This is preliminary integration with ocluster: This PR only adds an ocluster to the development docker, but it doesn't actually change the pipeline to use workers. It can be helpful to play with workers though, and more integration will follow soon!

Some things to note:

• The capnp-secrets contains the permissions to talk with the ocluster. The admin.cap is used by the pipeline in entrypoint.sh to generate submission.cap which can then be used to submit new jobs to the cluster.
• The workers need access to pool-linux.cap to receive jobs from the cluster (for that pool, you can add more, the linux name is arbitrary). By default, this file has cluster:9000 as the host... so you may need to edit it to a real IP or localhost:9000 or add cluster to your hosts.
• The local-test-repo should be specified in the development.env as an absolute path: Otherwise when the pipeline will submit jobs to the cluster, the workers will not be able to find the git repository (since they are running outside of the pipeline docker, the external path should be the same and not /app/local-test-repo).

See the OCluster readme for some commands to experiment with workers!

[gs0510]

LGTM! I have one question! Will it be possible to add two modes of starting the local dev mode? One cluster and one without one? What do you think about this idea? :)

[art-w]

I am a bit conflicted: It would be convenient to ease development, but would also require to maintain two different build-and-run setup (one in ocurrent for the pipeline, and one for the worker).

[art-w]

Redundant and less uptodate than #216