[#1449] tree: Add ApplyBatch method

Concurrent Apply can lead to child node applies before parent, so
undo/redo operations will perform. This leads to performance degradation
in case of tree with many sublevels.

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/services/tree/service.go

@@ -55,6 +55,7 @@ func New(opts ...Option) *Service {
 	s.replicatorChannelCapacity = defaultReplicatorCapacity
 	s.replicatorWorkerCount = defaultReplicatorWorkerCount
 	s.replicatorTimeout = defaultReplicatorSendTimeout
+	s.syncBatchSize = defaultSyncBatchSize
 	s.metrics = defaultMetricsRegister{}
 
 	for i := range opts {