[Added WPS softAP registrar example and events](https://github.com/espressif/esp-idf/commit/924c709efe71b2dfeea1991657f26d035f9e7b17#diff-f7913461d9e446aa95e17e595db9c1730a97b37a08f8f4c5e09052f770bf75bbR30)