[mle] allow attach and link sync between different Thread versions (#3779)
[mle] allow attach and link sync between different Thread versions (#3779)


turon/openthread,lanyuwen/openthread,librasungirl/openthread,jwhui/openthread,abtink/openthread,chshu/openthread,lanyuwen/openthread,chshu/openthread,openthread/openthread,abtink/openthread,lanyuwen/openthread,chshu/openthread,openthread/openthread,abtink/openthread,jwhui/openthread,jwhui/openthread,srickardti/openthread,bukepo/openthread,jwhui/openthread,srickardti/openthread,lanyuwen/openthread,abtink/openthread,turon/openthread,srickardti/openthread,bukepo/openthread,openthread/openthread,lanyuwen/openthread,srickardti/openthread,turon/openthread,librasungirl/openthread,openthread/openthread,bukepo/openthread,bukepo/openthread,chshu/openthread,turon/openthread,chshu/openthread,chshu/openthread,lanyuwen/openthread,librasungirl/openthread,librasungirl/openthread