test(Keys): Send a note to a not-yet-deployed contract

[benesjan]

It is a requirement that we can send a not to an account which has not yet been deployed.

Implement this non-inclusion proof and a test in which we demonstrate that it's possible to send a note to a not yet deployed contract.

Here is a comment from Mike on how the flow is supposed to work:

So the idea is that the preimage of the user's address contains their initial set of keys. So let's say you come along and say "Mike, I'd like to send you some money on this cool new blockchain called Aztec. Mike, you need to generate an address first."... then I'll say "Ok Jan, I've followed a tutorial and I've generated an Aztec address. Here is all the information you need". Mike (that's me) wouldn't send you just the address. He would need to send you the preimage of the address to. I.e.

• partial_address: Field (Palla designed the preimage layout this way, so that I don't need to send you all the contract class stuff)
• my master public keys
• contract_address

Jan (that's you) then can re-hash to check that hash(hash(...mike_public_keys), partial_address) == mike_contract_address

You can then use my Ivpk to send me notes.

We might be able to optimise the layout of the public_keys_hash even more, so that I don't need to provide you with all of my keys; just the Ivpk.

So the flow might be:

• Ask Mike for his address (and the preimage stuff). We could call this a "full address" or something pretty.
• Does mike's contract address exist on-chain?
  • If yes, has he registered keys in the registry?
    • If yes, use those registererd keys
    • If not, use the keys in his address preimage
  • If not, use the keys in his address preimage