Currently, the backend part of the repo is put in a subdirectory services/, and all the "client" part (i.e. the Jenkins Essentials distribution = Jenkins + evergreen-client) is all at the repo root.

This is a bit unsettling. We should reorganize this now, 1) because it would make things a bit clearer, and 2) because if/as additional people are going to work on this, this is nice to improve this before they start.