Update LISTEN/NOTIFY usage to a logical-replication based approach

[spwoodcock]

Is your feature request related to a problem? Please describe.

• Currently the LISTEN/NOTIFY approach requires a trigger on insert into the audits table of Central.
• An alternative approach that does not require a trigger at all, could be to use logical replication / logical decoding built into Postgres.
• This is the approach taken by https://github.com/Nextdoor/pg-bifrost and suggested by Sadiq Khoja at ODK.

Note

Perhaps this would have been the best approach from the start, but I wasn't aware this was possible until the implementation was mostly done using LISTEN / NOTIFY!

Describe the solution you'd like

• Assess the feasibility of swapping the approach / if it is more appropriate.
• Create a prototype and compare to current implementation.
• Accept or reject the change to logical replication.
• Update users about breaking change to tool if needed.