In this commit, we change the key stored within the internal order kit
into a raw pubkey array. Along the way we fix a bug in the verifier
tests due to using a map with pointer keys rather than the actual value
itself.
This commit aims to address a current gap within the system where trader
account states can become desynchronized if they participated in a batch
and they never received a Finalize message from the auctioneer.
From now on, if an account spend arrives while a trader has a pending
batch, then we assume they weren't able to receive its Finalize message,
and use the spend as an indication that the batch has been finalized.
This works because if a trader signs for a batch and disconnects, the
batch should have already been persisted, and if the batch was actually
finalized (i.e., broadcast without any changes), then the account should
have been spent.
This commits serves as preparatory work for committing a pending batch
before providing signatures to the auctioneer. This is achieved by first
storing the batch as pending upon receiving a new batch and marking it
as complete upon receiving a finalize message.
