soc unit tests have not been included when compiling with CMake,
because ../${SOC_NAME}/test was not evaluated relative to the
CMakeLists.txt directory.
Also call register_components() regardless of the presence of test
directory for particular target.
New unity component can be used for testing other applications.
Upstream version of Unity is included as a submodule.
Utilities specific to ESP-IDF unit tests (partitions, leak checking
setup/teardown functions, etc) are kept only in unit-test-app.
Kconfig options are added to allow disabling certain Unity features.
