[icmp6] pass Echo Request messages to user-defined callback (#3083)
[icmp6] pass Echo Request messages to user-defined callback (#3083)


LeZhang2016/openthread,openthread/openthread,gandreello/openthread,srickardti/openthread,erja-gp/openthread,abtink/openthread,srickardti/openthread,erja-gp/openthread,librasungirl/openthread,bukepo/openthread,chshu/openthread,librasungirl/openthread,gandreello/openthread,jwhui/openthread,gandreello/openthread,gandreello/openthread,gandreello/openthread,lanyuwen/openthread,openthread/openthread,chshu/openthread,librasungirl/openthread,erja-gp/openthread,LeZhang2016/openthread,lanyuwen/openthread,chshu/openthread,erja-gp/openthread,openthread/openthread,bukepo/openthread,lanyuwen/openthread,abtink/openthread,LeZhang2016/openthread,lanyuwen/openthread,LeZhang2016/openthread,turon/openthread,turon/openthread,LeZhang2016/openthread,srickardti/openthread,lanyuwen/openthread,LeZhang2016/openthread,chshu/openthread,turon/openthread,lanyuwen/openthread,erja-gp/openthread,srickardti/openthread,abtink/openthread,erja-gp/openthread,turon/openthread,openthread/openthread,librasungirl/openthread,jwhui/openthread,jwhui/openthread,jwhui/openthread,chshu/openthread,bukepo/openthread,gandreello/openthread,abtink/openthread,chshu/openthread,bukepo/openthread