Add signed auction result to bundle API

[itamarreif]

The Auctioneer needs to submit the auction results to the sequencer for the results to be read by the Rollup during block execution.

The result of the auction is a Bundle, which is serialized into a RollupDataSubmission action and submitted to the sequencer-level (i.e. signed and paid for by the Auctioneer's sequencer-level account).

The Rollup will receive RollupDatas with the sequenced data, and it will look for the Auctioneer's signed Bundle object for transactions to unbundle and place first in the block.

The Rollup will need to verify the Auctioneer's signature, which will have to be serialized into the RollupDataSubmission since the sequence does not include those in the RollupData events it creates from actions.

┆Issue Number: ENG-998

[joroshiba]

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