* programatically rename unique and foreign key constraints to enforce 'tablename_uq' and 'reftable_fkey' patterns
* manually rename unique constraints for names over 63 characters
* update changed constraint names in db update testcases
The new `ExternalName` field is an optional field that is used to store
the cloud providers' human-identifiable name for a given compute
instance. This field is not user-editable, but it is kept in sync with
the cloud provider's through Boundary's `SetSyncJob`.