Allow usage of private ips

Description

Add a configuration option to config.json that allows the usage of private ips. See https://docs.nodebb.org/configuring/config/ for current options.

Use case: Run NodeBB in your local network for testing purposes. As I need it to integrate nodebb to funfedi.dev

See https://codeberg.org/helge/containers/src/branch/nodebb.

Community forum reference

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