feat: add getIssuerForBrand to zoe

[dtribble]

closes: #1270

This adds getIssuerForBrand to zcf so that contracts can synchronously get issuers for amounts they receive. (We could add one to get it from an Amount as well.) The also adds type declaration.

This also modifies multipool autoswap to return the issuers etc. when a pool is added, rather than jut an acknowledgement string.

Testing

There is no existing test for getBrandForIssuer. The test for this new operation should be added with that. The operation currently gets ad hoc testing because the subsystem tests or dapp-token-economy relies on it.

The tests for multipool autoswap were updated are updated to accomodate and test that the new return result returns a record with at least some expected fields.

Documentation

This adds a new operation to ZCF, which should be added to the API documentation site.

This changes the return result of creating a multipool autoswap. The previous return was just a worthless string. Now we can get the issuers, etc. That's not currently documented, but could be extended with that information.

[katelynsills]

This looks good. Before merging can we add a unit test and coordinate with @tyg to change the documentation?

[katelynsills]

I think there are some linting errors and we might need to rebase this on master for only the wanted changes to show. Can we also add unit tests for this and coordinate with Tom on updating the documentation?

[dtribble]

This looks good. Before merging can we add a unit test and coordinate with @tyg to change the documentation?

I don't seem to be able to reply in-line so I'm not sure what lines of code the comments are attached to. I have a lint-fix.

Re unit tests, there aren't currently unit tests for the code I copied from (getBrandForIssuer). Add them to that list! I think we can delay that for the updated API, though.

Re documentation: it's additive. I'll update the PR comment with a doc section. I'm not sure why it didn't offer me a PR template.

[katelynsills]

Added a test, @dtribble do you want to take a look at it? I also asked Chris to review

[Chris-Hibbert]

These look like useful helpers. I'm skeptical about adding a helper for the tests and not invoking it anywhere.

[katelynsills]

These look like useful helpers. I'm skeptical about adding a helper for the tests and not invoking it anywhere.

I'm not sure what you mean. zcfTesterContract.js is run as the main part of this test, so everything added is invoked

[Chris-Hibbert]

zcfTesterContract.js is run as the main part of this test, so everything added is invoked

Thanks, I was looking for makeContract and missed that the file was imported explicitly.