Updater lifetime callbacks

[mcspr]

follow-up of https://github.com/esp8266/Arduino/pull/8598 we removed some WiFiClient stopAll(s) from updaters, make some lifetime callbacks similar to ArduinoOTA ones so it can be handled by the user

arduino ota part is not 'proxied' to updater counterparts, since the idea there is to track things specific to arduino ota and not anything global

not tested