Integrate nodes-lib tests in CI

[m0ar]

The nodes-lib test suite has a bunch of integration tests against desco-server related to publishing, signing, etc. It calls endpoints and tries to verify pre and post conditions in the db. With this suite continuously running, we can expand it and catch a lot of errors before they affect the webappp.

This has not yet been included in the nodes repo CI because it relies on services we haven't run there before, and requires a bit of novel setup.