There are a few major areas in this change.
CMake options are now located in a common cmake/NNGOptions.cmake file. This should make it easier for folks to figure out what the options are, and how they are used.
Tests are now scoped with their directory name, which should avoid possible name collisions with test names.
A number of tests have been either moved or incorporated into the newer testutil/acutest framework. We are moving away from my old c-convey framework to something easier to debug.
We use CMake directories a bit more extensively leading to a much cleaner CMake structure. It's not complete, but a big step in the right direction, and a preview of future work.
Tests are now run with verbose flags, so we get more test results in the CI/CD logs.