Async builder function signatures

[yknl]

This PR makes the transaction builder functions async. This is to enable automatic handling of nonce values in the future. The nonce value will be retrieved from a core node API and requires a network request.

Builder functions affected: makeSTXTokenTransfer makeSmartContractDeploy makeContractCall

New usage example:

const transaction = await makeSTXTokenTransfer(...);

or

makeSTXTokenTransfer(...).then((transaction) => {
  // do something with transaction
});

Type of Change

• [x] New feature
• [ ] Bug fix
• [ ] API reference/documentation update
• [ ] Other

Does this introduce a breaking change?

Yes makeSTXTokenTransfer makeSmartContractDeploy makeContractCall

Are documentation updates required?

Yes.

Testing information

npm run test

Checklist

• [x] Code is commented where needed
• [x] Unit test coverage for new or modified code paths
• [x] npm run test passes
• [ ] Changelog is updated
• [ ] Tag 1 of @yknl, @zone117x, @reedrosenbluth for review

[kyranjamie]

Is there a use case in which a consumer would want to manage the nonce themselves, for some reason, and thus circumvent the request, thus needing something like makeSTXTokenTransferSync?

[yknl]

Is there a use case in which a consumer would want to manage the nonce themselves, for some reason, and thus circumvent the request, thus needing something like makeSTXTokenTransferSync?

Yes I think that's a valid use case. We should be able to add that option.

[hstove]

Yeah - I find this change unnecessary for my use case. If we do add support for automatic fetching of nonce, then we should do so in a separate function. I don't want this library to handle nonce fetching (for the authenticator's use case), because that can run into issues when you have multiple unconfirmed TXs.

[yknl]

Sounds like we'd prefer to keep the transaction builder functions synchronous and have separate async nonce and fee estimation functions. Going to close this PR for now.