[Feature Request] Allow to export and import yggdrasil keys

[cofob]

Hello! It is currently impossible to export/import the yggdrasil keys (only public key is visible), as well as change the NodeInfo values (and NodeInfoPrivacy). Please add this functionality as it would be very useful for restricting a firewall to specific addresses or for identifying addresses.

[vikulin]

Identifying addresses uses only public keys not a private one. NodeInfo changes would be an another task.

[cofob]

But I can identify address on map by NodeInfo["name"] value