confirmsarray of MsgConfirmBatch
When validators observe a MsgRequestBatch they form a batch by ordering
transactions currently in the txqueue in order of highest to lowest fee,
cutting off when the batch either reaches a hardcoded maximum size (to be
decided, probably around 100) or when transactions stop being profitable
(TODO determine this without nondeterminism) This message includes the batch
as well as an Ethereum signature over this batch by the validator
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