Native VotingKey file generation

[fboucquez]

Instead of using catapult tools via docker run, bootstrap should generate the voting key natively in typescript.

This will:

• Speed up the config
• Remove docker from the requirement

This is pretty much a must-have if we want to bootstrap offline without requiring the node admin to also install catapult tools in the offline machine.

@gimer , could you guide me? Where can I find source code and docs to implement the catapult.tools.votingkey in typescript? Is it too complicated?

[gimre-xymcity]

first you have a header:
start-epoch (8b),
end-epoch (8b),
last key identifier (8b) - for fresh file this is 0xFFFF'FFFF'FFFF'FFFF (a.k.a. Invalid_Id)
last wipe key identifier (8b) - again, for fresh file this is 0xFFFF'FFFF'FFFF'FFFF (Invalid_Id)
root public key (32b) - this is root public key that is getting announced via vote link tx
start-epoch (8b), \ those two are exactly same one, as top level, reason is this was earlier a tree,
end-epoch (8b), / and each level holds this separately, so we left it as is

what follows are bound keys, there are (end - start + 1) of them.
each key is:
random PRIVATE key (32b)
signature (64b)

now the signature is usual signature done using ROOT private key on a following data:
(public key (32b), identifier (8b))

root private key is discarded after file is created.

identifier is simply epoch, but, most importantly keys are written in REVERSE order.

i.e. say your start-epoch = 2, end-epoch = 42
header:
2, 42, ff.., ff..., (root pub), 2, 42
keys:
(priv key 42, sig 42), (priv key 41, sig 31), ..., (priv key 2, sig 2)

every priv key should be cryptographically random,