SECURITY LABEL .... ON COLUMN is not propagated.

[emelsimsek]

Extension anon use case requires SECURITY LABEL ... ON COLUMN statements.

Citus only propagates SECURITY LABEL ... ON ROLE commands.

To enable anon extension use cases, we need to propagate ON COLUMN security labels as well.

Workaround could be to run SECURITY LABEL ... ON COLUMN on all nodes manually.