A transaction class that can encode and decode from an RPC transaction dict

[fselmo]

What feature should we add?

There should be an easy way to take a transaction directly as a JSON-RPC dict and put it into an object that can encode() and decode() the transaction. This would behave much like the TypedTransaction class does for typed transactions in eth-account - and in fact this class can probably carry a lot of the heavy load here - but it also needs to clean up certain fields based on the type in order for it to even be plugged into the TypedTransaction class.

I'm thinking something like:

>>> from web3.utils import Web3Transaction

>>> # from dict
>>> txn = Web3Transaction.from_dict(w3.eth.get_transaction("0x..."))
>>> txn.encode().hex()
02ed01808504a817c8008504a817c800830186a09400000000000000000000000000000000000000008080c0808080...

>>> # from bytes
>>> txn = Web3Transaction.from_bytes(b'\x02\xed\x01\x80\x85\x04\xa8\x17\xc8\x00\x85\x04\xa8\x17\xc8\x00\x83\x01\x86\xa0\x94\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x80\x80\xc0\x80\x80\x80')
>>> txn.as_dict()
{
    "chainId": 1,
    "maxFeePerGas": 20000000000,
    "maxPriorityFeePerGas": 20000000000,
    "nonce": 0,
    ...
}

>>> # fields accessible as properties
>>> txn.max_fee_per_gas
20000000000

Or, maybe it's a HexBytes as the result of encode(). Either way, I think the utility here is fairly clear. Take a transaction straight from a result, put it into a utility class, and be able to manipulate and have useful methods available on the transaction.

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