* Description of unregistering was incorrect
* Made clear that event loop arg mustn't be NULL
* Added parameter check in create function
Closes https://github.com/espressif/esp-idf/issues/6761
Closes IDFGH-4969
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.