esp_console_cmd_register() function

- ESP_OK on success - ESP_ERR_NO_MEM if out of memory - ESP_ERR_INVALID_ARG if command description includes invalid arguments - ESP_ERR_INVALID_ARG if both func and func_w_context members of cmd are non-NULL - ESP_ERR_INVALID_ARG if both func and func_w_context members of cmd are NULL

If the member \c func_w_context of cmd is set instead of func, then the member \c context is passed to the function pointed to by \c func_w_context.