feat: support keypairs for spells [NET-237 NET-239 NET-281 NET-283]

[justprosh]

• added ("scope" "get_peer_id") builtin that returns the existent peer id of keypair associated with INIT_PEER_ID or generates and stores a new one
• ("spell" "install) and ("spell" "remove") are operating with scope peer_id
• all spell particles sent on behalf of scope peer_id
• spells deployed by the same peer_id share the same keypair (just like spells deployed by other spells)

BEGIN_COMMIT_OVERRIDE
feat: support keypairs for spells [fixes NET-237, NET-239, NET-281 and NET-283] #1382
END_COMMIT_OVERRIDE

[linear]

NET-237 Sign spell particles with owner-specific keypair

NET-239 Support addressing spells via PeerId derived from owner-specific keypair

(call relay (op noop) [])
(call spell (spell_id set_string) [key value])
-- `spell` is a PeerId generated from spell's owner-specific keypair

NET-281 Builtin function to trigger owner-specific keypair generation

If such keypair doesn't exist, create it. Then always return the PeerId of the owner-specific keypair.

Most likely will always be called before spell.install

NET-283 Generate random keypair for each `owner_id` on the same host

[folex]

So much better!

How about the following API:

spell_service.extend(hashmap!{
  "install" => self.make_spell_install_closure(),
  "remove" => self.make_spell_remove_closure(),
  ...
})

[folex]

But current approach is nice as well. So maybe keep it.

[folex]

nicely done!