etcdserver: support structured logging for auth
etcdserver: support structured logging for auth

Signed-off-by: Gyuho Lee <3454051ee3341eb69bdf6fca40899cdad4d86496@gmail.com>

etcd-io/etcd,xiang90/etcd,dannysauer/etcd,coreos/etcd,mqliang/etcd,xiang90/etcd,joshix/etcd,li-ang/etcd,rnaveiras/etcd,li-ang/etcd,vimalk78/etcd,sebrandon1/etcd,bdarnell/etcd,ajityagaty/etcd,sinsharat/etcd,mqliang/etcd,mkumatag/etcd,fanminshi/etcd,mkumatag/etcd,ajityagaty/etcd,etcd-io/etcd,mqliang/etcd,rnaveiras/etcd,fanminshi/etcd,sinsharat/etcd,vimalk78/etcd,bdarnell/etcd,gyuho/etcd,etcd-io/etcd,cockroachdb/etcd,mkumatag/etcd,rnaveiras/etcd,coreos/etcd,cockroachdb/etcd,glevand/coreos--etcd,glevand/coreos--etcd,sebrandon1/etcd,joshix/etcd,gyuho/etcd,ajityagaty/etcd,dannysauer/etcd