* wifi: ARP gratuitous API for wifi station mode
* fix with lwip1
* update comment
* update API to allow changing interval on the fly
* update API
* remove debug lines
* mock lwIP's etharp_request()
* unsigned interval
* use scheduled ticker
* ticker: +attach_ms_scheduled_accurate
ticker: +comment
gratuitous: use attach_ms_scheduled_accurate
* move to experimental namespace
* fix for lwIP-v1.4
* attempt to make pio happy
* use directly ETSTimer instead of Ticker
