Comp backend: collect metrics and send in RabbitMQ

[sanderegg]

We need to collect start/stop times and update every now and then when a computational service is running for resource tracking purposes.

In order to track resource usage we need that:

• [x] director-v2 publishes events when a service starts,
• [x] stops,
• [x] heartbeat while the service is running

[sanderegg]

completed via https://github.com/ITISFoundation/osparc-simcore/pull/4570