MUSCLE3 datasource

[maarten-ic]

TODO:

• Merge Implement option to only consume most recent data on the Kafka topic #11 and update setting for most_recent_only
• Update version constraint for muscle3 -- requires next release for default values of settings
• Discuss yMMSL import mechanism entry points and update if needed
• Update test (which depends on the yMMSL import mechanism) to prevent CI failure