Peers discovery via N2C or N2N

[matiwinnetou]

Please provide support for ability to see all peers to which Cardano-Node is connected via n2n or n2c. We our issue cardano-foundation/cardano-rosetta-java#450, we must not return empty peers array but actually something meaningful, this data is dynamic.

[matiwinnetou]

Perhaps there could be some singleton or singleton alike object (e.g. managed by dependency injection framework) that always in memory has the list of all peers with ability to list them, filter them if necessary on the client side, hostname and port plus what is available via mini protocols.