Currently, we are only generating per Event class compose with the RPMs to inject to rebuild Container image, but we also need to generate ODCS compose to define the set of repositories with released RPMs per ArtifactBuild.

This is done in https://pagure.io/freshmaker/pull-request/113, but it uses blocking mechanism. We should wait for ODCS state change message instead. To do this, following must be done:

• Add ArtifactBuild.compose_id similar to Event.compose_id.
• Change ErrataAdvisoryRPMsSignedHandler._prepare_pulp_repo to not wait for the end of compose.
• In _record_batches, store the resulting compose id to ArtifactBuild.compose_id instead of to build_args.
• In ComposeStateChangeHandler, search also for ArtifactBuilds based on the ArtifactBuild.compose_id and build first batch only when all the compose_ids for the events are "done".