How does CRW construct a workspace?

Issue

CodeReady Workspaces makes a workspace on demand for a user. The provided devfiles usually contain a language plugin and a runtime image for the given language environment.

Examining the Pod that has the workspace containers, we see other containers present:
- A few init containers. One for a runtime injector and one for a plugin broker.
- JWTProxy, Machine exec, and Theia.
Where do these come from? They are not in the devfile!