Improvements for Downstream Packaging

[dvn0]

As mentioned in https://github.com/simplex-chat/simplexmq/issues/731#issuecomment-1666541728 [*] there are multiple areas that could use cleaning up and documentation in order to make it easier for packaging and deploying the simplexmq servers.

[*]

hardcoded file-system paths, the user is expected to initalize it by running it as root, and the configuration isn't documented.