[onchain] Factory creation

Introduction of the Factory to deploy blank accounts without calldata and upgrade them to the actual vault account. The deployment method is protected and only callable by the owner.

This factory allows to have fully deterministic vault accounts addresses based on the salt used. This way, if we use a hash of the phone number, all future Vault accounts have a deterministic address that we can fund even if the user doesn't have an account yet.

The blank account is useful in case we want to update the Vault Account. By using the intermediate class hash of the Blank account for the deployment, we can update the Vault account class hash without breaking compatibility with previous address determination algo.

keep-starknet-strange / vault

[onchain] Factory creation #81