Added port configuration for praefect database

What does this Merge Request do?

This allow praefect to get port configuration. This is needed when either configuring the main database to accept TCP connection, or even when using unix sockets, the port is configured to something else, as the port number is appended as part of the unix socket name.

Merge Request checklist

• Tests added for new functionality. If not, please raise Issue to follow-up.
• This change is backward compatible. If not, please include steps to communicate to our users.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.