docker: install jq in base image

[kba]

For doing JSON query ops in derived containers. Small and few dependencies and we do need it for the readinessProbe of the processing worker pods:

curl -u "*:*" -s http://$(OCRD_RABBITMQ_SERVICE_HOST):15672/api/queues | \
jq '.[] | select(.name == "$(OCRD_PROCESSOR_NAME)")' >/dev/null || exit 1

[kba]

Test failures are due to the issue fixed in #1356

[bertsky]

Absolutely!