Add a way to specify that Pool deposit is not required for add_change_if_needed()

[0xtrossets]

Transactions with pool-registration certificate is assumed to require the pool-deposit (500ADA) when doing the automatic change calculation.

Pool deposit is only required if the pool is not yet registered. Pool registration certificates are still required to update pool-reg information like metadata, relays, etc, when the pool is already registered, and a deposit is not required.

We need a way to specify that the pool-reg cert is an update for an existing pool-reg, so that add_change_if_needed() can calculate the change properly.

[lisicky]

Hi @0xtrossets ! Thanks for your issue. Until we add the function for that case you can try to set zero pool_deposit in TransactionBuilderConfig as workaround.