Fix Fetch.fetchActions and add new fetchActions method for external use

[Comdex]

• Fix Fetch.fetchActions

When sending actions in the following ways, an error will be reported when using the existing getActions method to get actions data：

let tx = await Mina.transaction(
        {
          sender: feePayerAddress,
          fee: txFee,
        },
        () => {
          zkapp.doSomething(); // dispatch 1 action
          zkapp.doSomething(); // dispatch 1 action
        }
);

This problem only occurs when there are multiple actions corresponding to multiple AccountUpates in the same transaction, which is basically caused by a bug in Fetch.fetchActions that the getActions method depends on.

It can be reproduced using snarkyjs version 0.9.6 under the current Berkeley network:

 // This fetchActions method is not exported for external use in current version
 let actions = await fetchActions({
        publicKey: 'B62qqfgrF56mGyqNXsyd6iMqwWDQVC9KKcLVwcToLwfNg5ju2tVwSn5',
        actionStates: {
          fromActionState: Reducer.initialActionsHash.toString(),
        },
      });
 console.log('actions: ', JSON.stringify(actions));

• Add two new fetchActions methods for exporting to be used externally

Currently, we don't have any methods that can be called outside the smart contract to get actions from the network.
So it is proposed to add two new asynchronous methods to solve this problem(Compatible with LocalBlockChain and Network):

// Mainly returns data in string form
Mina.fetchActions(publicKey, {fromActionState, endActionState}, tokenId)
// Return data as ActionType
SmartContract.reducer.fetchActions({
    fromActionState,
    endActionState,
})

[mitschabaude]

Thanks @Comdex for adding the new fetch functions! Having them is consistent with the rest of the API, and useful.

I'm a bit worried that if there was a bug in fetchActions, this PR doesn't fix it

[mitschabaude]

Is this supposed to fix the bug that you mention? If so, I don't see how it can. The if branch is only executed when we had accountUpdateId === currentAccountUpdateId, so the new line currentAccountUpdateId = accountUpdateId; does nothing

[Comdex]

Yes, this is a simple fix, in fact you can see that the currentAccountUpdateId will be updated after the other branches end, and this problem is caused by the lack of this processing due to the direct return

[mitschabaude]

I don't follow. Can you explain how setting currentAccountUpdateId to accountUpdateId can change anything if currentAccountUpdateId is already equal to accountUpdateId, which was tested in the line above (isSameAccountUpdate)?

[Comdex]

@mitschabaude Got you, I made a mistake, lol 😂
Please ignore this modification
I will make a new pull request with the correct fix