Issuer test cases for status entry and status credential

[PatStLouis]

This PR adds tests for normative statements around the status entry object and status credential object.

The message feature and statusSize feature are not implemented currently.

[aljones15]

unless I'm not getting something you got confused on what are should chai assertions and basic javascript API calls, but that's not that hard of a mistake to make.

[TallTed]

Just a plural/singular fix

[PatStLouis]

Whenever you have time, all comments should have been addressed

[aljones15]

I am approving just so we get code into main. There are things to be done here, but I think this is a really solid start to status list.

[BigBlueHat]

More tweaks, but I fear if they're not addressed now they'll be painful to (re)find later.

Thanks!
🎩

[BigBlueHat]

.exist is a property, not a method, in Chai (afaik):
https://www.chaijs.com/api/bdd/#exist

Additionally, it seems there's a good bit more to test here with more specificity.

[PatStLouis]

I'm assuming that if the sl.decodeList({encodedList}) returns a response, the encoding was done properly since that decodeList function will only work if encoded properly.

[PatStLouis]

I'm not sure what action you want me to take with the exist statement as it serves the intended purpose, to make sure the value exists

[PatStLouis]

In the should extras, it says that by assigning should to a variable you have access to some quick helpers, including exist:
https://www.chaijs.com/guide/styles/#should

[TallTed]

Small, editorial.

[aljones15]

Approving again to allow initial batch of tests to main.