Add dry-run mode to nostrss core

[Asone]

Is your feature request related to a problem? Please describe.
Issue #86 makes quite obvious there could be some value on being able to run nostrss program without sending actually any real notes for debug purposes. This would allow to generate logs to see how the program behaves without broadcasting any real data, which could be useful in case of potential bugs that would be suspected to spam the network.

Describe the solution you'd like

The program could take an argument dry-run which would only create an output in logs instead of broadcasting notes over the network.

[rottenwheel]

@Asone FYI, #86 happened/is happening again with new version, running config posted in there as per your request.