Move "await_prepare" logic into authorize

[kdenhartog]

By moving this into the authorize logic so we make sure that both operators who are approving the transaction list are also checking that the transaction list is correct before authorizing the transactions. This would mean prepare would be ran by a single operator and be more like a "fire and forget" command where as authorize would be ran by multiple operators still and the transaction list will be validated by multiple operators too.

[kdenhartog]

I'd like to see us get to a point where the operator tooling is in a pretty stable state before we start issuing more invites, so this seems like a good one to keep as blocking at the moment.