feat: add utility lock and unlock commands

[Cafe137]

No description provided.

[attila-lendvai]

@Cafe137 this works great, thanks!

unfortunately, i have just realized that this only works for the blockchain key, which is enough when someone wants to mine a new node into a neighborhood. but just now, when i wanted to migrate a node from one environment to another, i realized that the other keys (libp2p_v2.key and pss.key) are also encrypted with the password, so i cannot migrate the node.

i'll probably proceed by changing my service code to assign a separate password for each node it starts, but i wanted to let you know about this uncovered use-case, too.