Add experimental support for Citus

[punktilious]

Is your feature request related to a problem? Please describe.
Citus is a distributed database extension for PostgreSQL.

Add distribution/replication information to the schema so that this metadata can be applied when the tables are created. Filter the creation of foreign key relationships according to the distribution rules.

Describe the solution you'd like
The schema tool should contain support for Citus databases.

Describe alternatives you've considered
Apply the Citus logic manually after the schema is created.

Acceptance Criteria

1. GIVEN [a precondition]
   AND [another precondition]
   WHEN [test step]
   AND [test step]
   THEN [verification step]
   AND [verification step]

Additional context
Does not support migration from an earlier version. The first Citus install must be FHIR schema version V0026.