This updates the minimal supported version of CMake to 3.16, which in turn enables us to use more CMake features and have a cleaner build system.
This is the version that provides most new features and also the one we use in our latest docker image for CI.
* Migrate test cases from IDF test runner to Unity fixture.
* Tighten heap checks in the test case a bit.
* Run formatting script on test_wl.c
* NEW: Define 4 test configurations, including configs with 512 byte
sector size. Previously these configs weren't tested in CI.
* NEW: The test app only runs for ESP32 and ESP32-C3 (one chip for
each architecture). The component is pretty high level so we don't
need to test it for each chip. This reduces the load on CI.
