[Non-breaking changes] Optimize receipt storing

[trinhdn2]

This PR attemps reduce the size of RLP encoded transaction receipts, also backwards compatibility is ensured.

These PRs must be merged first:

• [Non-breaking changes] Update RLP library and RLP encoder code generation tool for structs #358

Instead of storing a full RLP encoded receipt including

type legacyStoredReceiptRLP struct {
	PostStateOrStatus []byte
	CumulativeGasUsed uint64
	Bloom             Bloom
	TxHash            common.Hash
	ContractAddress   common.Address
	Logs              []*LogForStorage
	GasUsed           uint64
}

we only need to store these crucial fields

type StoredReceiptRLP struct {
	PostStateOrStatus []byte
	CumulativeGasUsed uint64
	Logs              []*Log
}

the rest information can be derived from context and chain config

// DeriveFields fills the receipts with their computed fields based on consensus
// data and contextual infos like containing block and transactions.
func (rs Receipts) DeriveFields(config *params.ChainConfig, hash common.Hash, number uint64, txs []*Transaction) error {
	signer := MakeSigner(config, new(big.Int).SetUint64(number))

	logIndex := uint(0)
	if len(txs) != len(rs) {
		return errors.New("transaction and receipt count mismatch")
	}
	for i := 0; i < len(rs); i++ {
		// The transaction type and hash can be retrieved from the transaction itself
		rs[i].TxHash = txs[i].Hash()

		// block location fields
		rs[i].BlockHash = hash
		rs[i].BlockNumber = new(big.Int).SetUint64(number)
		rs[i].TransactionIndex = uint(i)

		// The contract address can be derived from the transaction itself
		if txs[i].To() == nil {
			// Deriving the signer is expensive, only do if it's actually needed
			from, _ := Sender(signer, txs[i])
			rs[i].ContractAddress = crypto.CreateAddress(from, txs[i].Nonce())
		} else {
			rs[i].ContractAddress = common.Address{}
		}

		// The used gas can be calculated based on previous r
		if i == 0 {
			rs[i].GasUsed = rs[i].CumulativeGasUsed
		} else {
			rs[i].GasUsed = rs[i].CumulativeGasUsed - rs[i-1].CumulativeGasUsed
		}

		// The derived log fields can simply be set from the block and transaction
		for j := 0; j < len(rs[i].Logs); j++ {
			rs[i].Logs[j].BlockNumber = number
			rs[i].Logs[j].BlockHash = hash
			rs[i].Logs[j].TxHash = rs[i].TxHash
			rs[i].Logs[j].TxIndex = uint(i)
			rs[i].Logs[j].Index = logIndex
			logIndex++
		}
	}
	return nil
}

The backwards compatibility of the DecodeRLP method of a receipt is ensured. It will try to RLP decode based on the new receipt format first, if there is any error it will use the old legacyLegacyStoredReceipt RLP format.

// DecodeRLP implements rlp.Decoder, and loads both consensus and implementation
// fields of a receipt from an RLP stream.
func (r *ReceiptForStorage) DecodeRLP(s *rlp.Stream) error {
	// Retrieve the entire receipt blob as we need to try multiple decoders
	blob, err := s.Raw()
	if err != nil {
		return err
	}
	// Try decoding from the newest format for future proofness, then the older one
	// for old nodes that just upgraded. V4 was an intermediate unreleased format so
	// we do need to decode it, but it's not common (try last).
	if err := decodeStoredReceiptRLP(r, blob); err == nil {
		return nil
	}
	return decodeLegacyStoredReceiptRLP(r, blob)
}