This refactor is only for backwards compatible.
It piggybacks on the console example to add ping support and CLI. Merges https://github.com/espressif/esp-idf/pull/4093
1. Add command for Ethernet based on console component. 2. Make cmd_system and iperf a component that can be referenced by other examples 3. Add "version" command to cmd_system.c 4. Clean up the README.md in all ethernet examples[TW#26525]