annotate all test config files

[tgross]

currently the test configuration files for both unit tests and integration tests are all JSON5 but not necessarily in a consistent format. Annotating these with comments for the intent of each section will help us write docs for v3 and make the code base a bit more accessible.

[jwreagor]

Actually, came to write an issue for better test documentation specifically what each test is performing and why. The tests in CP are top notch but its tough to rummage through their source in order to uncover which tests are performing what behaviors (at least initially).

I believe this issue would address that.