Obey Law of Demeter for test code

[kentbull]

Feature request description/rationale

While looking through the test utilities and other code in the integration tests I noticed that many objects are passed around where values are sufficient and also that some places include multiple level of objects being accessed.

Generally it seems the Law of Demeter, or principle of least knowledge, makes code maintainable with lower cost than without so it would be worth refactoring the testing code to abide by this principle.

This issue is starting as a catch all. I will add specific examples as I come across them again.

[kentbull]

First example: test-util.ts:getIssuedCredential issuerAID and recipientAID arg that should just be prefixes.

[kentbull]

Next example / instance: test-util.ts:admitSinglesig recipientAid should be recipientPrefix