Provide new defined resources for managing pg_hba.conf

This patch provides a more advanced way of managing pg_hba rules, by providing a
defined resource to manage a pg_hba file, and a defined resource for managing
rules within such a file (pg_hba_rule).

These new resources are wrappers around ripinaar-concat, and utilise file
assemblies instead of a template to compose the pg_hba.conf file.

I've provided a function that interprets the old ip4|6acl arrays and converts
them to this new format for backwards compatibility as well.

I slightly reformatted our documentation to allow for better documentation of
defined resources in 'Usage' as well, and provided examples of how to use this
new resource.

This hopefully should go a long way to solving the PR's related to lack of full
functionality for pg_hba.conf.

Signed-off-by: Ken Barber <ken@bob.sh>
Do not run the reload of postgresql as postgresql

While this worked fine in Ubuntu, it failed silently in Centos.

The script is really designed to be ran as root, so removing the user
property. This was failing our new pg_hba_rule tests without it.

Signed-off-by: Ken Barber <ken@bob.sh>