A new Upload transaction to upload the huge bytecode on the chain

[xgreenx]

Related FuelLabs/fuel-core#1754 and FuelLabs/fuel-specs#570

The change adds a new Upload transaction that allows uploading huge byte code on chain subsection by subsection.

The Upload transaction is chargeable and is twice as expensive as the Create transaction. Anyone can submit this transaction.

Before requesting review

• I have reviewed the code myself

[MitchTurner]

Tangentially related:

Something I've said before, and I still think would be good is instead of Upload and Script and Create, etc, we should have our transactions named UploadTx and ScriptTx and CreateTx, etc. I know the context is in the namespace, but it is never with it's namespace, so unless you understand the context well, you have to make couple clicks before you understand what they are.

Event then, it's far from obvious that Script would be a type of transaction, to me Script suggests that it is the code run by smart contracts, and never what you'd use for a simple transfer (but it is what you'd use). So even ScriptTx probably isn't clear enough.

[MitchTurner]

I was gonna suggest maybe drying this up a little with a shared function:

fn transaction_round_trip_serde<T>()
    where 
        TransactionFactory<StdRng, T>: Iterator,
        T: Into<Transaction>
     {
    TransactionFactory::<_, Upgrade>::from_seed(1295)
        .take(20)
        .for_each(|(tx, _)| {
            // given
            let tx: Transaction = tx.into();
            // when
            let tx_p = tx.to_json();
            let tx_p = Transaction::from_json(tx_p).expect("failed to restore tx");
            // then
            assert_eq!(tx, tx_p);
}

I don't know if this is much better with all the generics.

I think the name to_from_str could be a little clearer either way though.