Long running executions support #189
Description
Right now b7s supports synchronous executions - Bless runtime process is started, we wait for it to complete, and respond with the outputs of the execution. This is primarily because we have been oriented towards short-lived executions, something that returns almost immediately.
Next thing we want is to be able to support long running executions - for example, you start something akin to a web server that will run run for hours and days. In that scenario, we want to start an execution job and detach.
The user/client is able to issue job control messages:
- query a job (resource usage and outputs so far)
- kill a job
- attach (sort of make it synchronous again - wait till the job is completed)