Add server-rpc-endpoint to api

[xloem]

It appears to me the only way to access both the wallet api and the blockchain apis is to connect to two services simultaneously (is that correct?).

This PR adds the blockchain server information to the wallet api, so that only one endpoint need be passed to a client app that uses both.

[abitmore]

IMHO this makes little sense. Having server info doesn't mean you're able to connect to the server, for example it can be behind a firewall. Actually info of cli_wallet itself is more sensitive than info of API nodes because cli_wallet may contain private keys, usually the cli_wallet should be deployed by you own, that said, you must have known info of the API node it connected already. Anyway, this is opensource software with a MIT license, you're free to modify the code locally if you need it.

[abitmore]

Perhaps we can do this in the scope of #626.

[xloem]

thanks for the link @abitmore .. sounds like my concerns might be under discussion and this isn't the best fix for others with e.g. firewalls.