kvdb: move channeldb/kvdb to top level

cluster/etcd_elector.go

@@ -6,7 +6,7 @@ import (
 	"context"
 	"time"
 
-	"github.com/lightningnetwork/lnd/channeldb/kvdb/etcd"
+	"github.com/lightningnetwork/lnd/kvdb/etcd"
 	"go.etcd.io/etcd/clientv3"
 	"go.etcd.io/etcd/clientv3/concurrency"
 	"go.etcd.io/etcd/clientv3/namespace"