[cli] add length check for "service add" (#3508)
[cli] add length check for "service add" (#3508)


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