Collator: initiate `shutter_submitBatch` on new decryption-keys

[ezdac]

A parallel process has to constanly check for new values of cltrdb.decryption_key (see #333 ).
Whenever there is a new key that corresponds with the last closed batch, the process has to:

• retrieve all committed on shutter-transactions from the DB for that epoch
• construct a new BatchTx including the rlp-encoded shutter-transactions, the determined l1-block-number (see #336 ), decryption key and additional metadata :

  type BatchTx struct {
      ChainID       *big.Int
      DecryptionKey []byte
      BatchIndex    uint64
      L1BlockNumber uint64
      Timestamp     *big.Int
      Transactions  [][]byte
  }

• submit the RLP encoded and signed BatchTx to the shutter_submitBatch JSON RPC endpoint at the sequencer
• eventually listen on the shutter_batchIndex endpoint to wait for successful submission of the batch

[ezdac]

#331 might be relevant for this to have a look at the reference implementation of the shutter_submitBatch method.
This test

rolling-shutter/rolling-shutter/mocksequencer/mocksequencer_test/decryption_test.go

Lines 52 to 60 in 7c8bce3

	batchTxInner := txtypes.BatchTx{
	ChainID: fixtures.ChainID,
	DecryptionKey: epochSecretKey.Marshal(),
	BatchIndex: nextBatchIndex,
	L1BlockNumber: l1BlockNumber,
	Timestamp: big.NewInt(time.Now().Unix()),
	Transactions: [][]byte{shtxBytes},
	}
	batchTx, err := txtypes.SignNewTx(fixtures.PrivkeyCollator, fixtures.Signer, &batchTxInner)

calls that method and sends a batch to the endpoint

[Deleted user]

Implemented in collator/batchsubmission.go