celery: Supports ewoks config from blissdata
This PR allow to optionally read the celery config from the ewoks config.
As it was done for sidecar.
The previous way to configure is still working
Here is the resulting config in the tomo demo session:
component: celery
ewoks_config: 'beacon:///ewoks/config.yml'
# broker_url: redis://localhost:10002/2
# backend_url: redis://localhost:10002/3
broker_dlq: true
broker_queue: default
beamline_queue: !include app.yml#meta_beamline
tasks: []