fix(signing): do not drop shardID for rlp encoding

[MaxMustermann2]

This change only impacts chainId >= 1666600000.

[MaxMustermann2]

Example of a signing by this corrected method is below. Note that the correction is independent of harmony-one/go-sdk#295, which adds the ability for a data field to hmy which is not used here.

$ wget -O hmy https://harmony.one/hmycli
$ chmod +x hmy
$ ./hmy transfer --offline-sign --nonce=0 --from=one1r8n7xah8cgfm0el8u3kvwzja6zrd4le2ntjy82 --to=one1r8n7xah8cgfm0el8u3kvwzja6zrd4le2ntjy82 --amount=1 --gas-limit=21000 --gas-price=100 --from-shard 0 --to-shard 1 --chain-id=1666600000 | jq '.[0] | ."raw-transaction"'
"0xf8728085174876e80082520880019419e7e376e7c213b7e7e7e46cc70a5dd086daff2a880de0b6b3a76400008084c6ac98a3a0322cca082c3ca0a1d9ad5fffb4dc0e09ade49b4b0e3b0c9dfa5f6288bc7363d6a05604874964abaaf364e8b10108e8bfed5561c341aa5e4abb92b2c6f4c009ef4c"

Same with Python

#!/usr/bin/python3

from pyhmy import signing

transaction_dict = {
    "chainId": 1666600000,
    "gas": 21000,
    "gasPrice": 100000000000,
    "nonce": 0,
    "shardID": 0,
    "to": "0x19e7e376e7c213b7e7e7e46cc70a5dd086daff2a",
    "toShardID": 1,
    "value": 1000000000000000000,
}
signed_tx = signing.sign_transaction(
    transaction_dict,
    "0x1111111111111111111111111111111111111111111111111111111111111111",
)
print( signed_tx.rawTransaction.hex() )
0xf8728085174876e80082520880019419e7e376e7c213b7e7e7e46cc70a5dd086daff2a880de0b6b3a76400008084c6ac98a3a0322cca082c3ca0a1d9ad5fffb4dc0e09ade49b4b0e3b0c9dfa5f6288bc7363d6a05604874964abaaf364e8b10108e8bfed5561c341aa5e4abb92b2c6f4c009ef4c