Add CERNBox to docker-based tests

[michielbdejong]

We should add a CERNBox configuration to https://github.com/cs3org/reva/tree/updated-sciencemesh-testing/examples/sciencemesh so we can test not only OC to OC, OC to NC, NC to NC and NC to OC, but also OC to CERNBox, CERNBox to OC, NC to CERNBox and CERNBox to NC.

@glpatcern do you think you can provide a config file that makes this possible?

[gmgigi96]

Yes we can provide it!

[glpatcern]

A bit more complex than initially thought: the idea is to be able to serve the (OCIS) UI from nginx, but that requires:

• completing Revamp ScienceMesh integration tests #4246
• implementing a "reva plugin" for the UI

[labkode]

• implementing a "reva plugin" for the UI

This one I'm working on it, WIP

[glpatcern]

This was eventually done with nginx, which mimics exactly what we run in production, as the "reva plugin" for the UI was not continued. Also the docker scripts were moved to https://github.com/sciencemesh/dev-stock.