Research: Compare pglogical extension to native logical replication

Currently, logical replication can be managed in PostgreSQL via the pglogical extension, or native logical replication (and possibly other methods). We should investigate the methods, and decide on which method better suits our needs.

Notes:

• GCP CloudSQL and AWS RDS currently support both methods
• omnibus-gitlab does not ship with the pglogical extension. It would need to be added.
• There is some internal usage of logical replication already. Feedback from teams already using logical replication should be sought out.