Instance launcher

The Instance launcher is an interface that defines methods the workflow engine needs to launch (run) workflow steps (Jobs). Execution of Jobs in the Squonk2 Kubernetes environment is a complex affair and the engine relies on logic that already exists in the DM to do this.

As well as defining the interface (an Abstract Base Class) that the DM implements the engine also defines LaunchParameters and LaunchResult dataclass objects that define the arguments to, and results received from, the launch() method.