List partitioning helper can cause deadlocks if the table to partition has foreign keys

In gitlab-com/gl-infra/production#7907 (closed), while trying to convert ci_builds_metadata to a partitioned table, the ALTER TABLE ATTACH PARTITION statement encountered a deadlock trying to acquire an AccessExclusiveLock on ci_builds.

That partition attachment statement takes an AccessExclusiveLock on the table to attach, and additionally each table that it references by foreign key.

Other application code routinely locks ci_builds followed by ci_builds_metadata. As a result, a deadlock occurred.

Change the partitioning helper to allow specifying a locking order, so that a deadlock is less likely.