warn for not using local stacks node with the signer

[ASuciuX]

Current Status: Waiting for FAQ section to add link to.

• fixes [stacks-signer] Add a log message to signer on bootup to warn that signer should only be run with a LOCAL node #4730

Example display of message. Do we want to place it on only one line? Maybe make the message shorter.

[hstove]

I think it could potentially cause more harm (or at least worry) than good if we're being strict about this warning with non-localhost setups. IMO it's probably best practice to have these two services on separate colocated machines, or at most using something like docker-compose, but we wouldn't really be able to check that. The main risk is that the signer isn't a registered event_observer, and that's easy to mess up if you're using an external node, but we don't have a good way of verifying that the signer is an event observer.

[jferrant]

I think it could potentially cause more harm (or at least worry) than good if we're being strict about this warning with non-localhost setups. IMO it's probably best practice to have these two services on separate colocated machines, or at most using something like docker-compose, but we wouldn't really be able to check that. The main risk is that the signer isn't a registered event_observer, and that's easy to mess up if you're using an external node, but we don't have a good way of verifying that the signer is an event observer.

Well the warning is mostly in response to the audit as we are susecptible to man in the middle type situations so perhaps we should just always print it then.

[ASuciuX]

Updated message displayed after having all of it as 1 line