PostgreSQL Module - pg_hba_rule defined type should be usable without managing a postgresql instance

From my own investigation into the postgresql module there is no way to manage pg_hba.conf without managing the full postgresql instance.

You can see in the code there are references to variables from outside of the defined type that make it so you cannot use it without defining postgresql::server first.

https://github.com/puppetlabs/puppetlabs-postgresql/blob/master/manifests/server/pg_hba_rule.pp#L18

https://github.com/puppetlabs/puppetlabs-postgresql/blob/master/manifests/server/pg_hba_rule.pp#L28

For my use case, I'd like to manage just the pg_hba.conf while someone else is managing the whole instance.