Flush last snapshot data

[le-vlad]

In case if amount of data in the snapshot is lower then batch size - we have to flush the snapshot before starting logical replication

[le-vlad]

Should be fixed in #3

[le-vlad]

Fixed with time.AfterFunc()

if len(s.messagesBuffer) >= s.snapshotMaxBufferSize {
			err := s.writeSnapshotBatch()
			if err != nil {
				return err
			}

			s.messagesBuffer = []message.Message{}
			return nil
		} else if s.snapshotTicker == nil {
			// Start a timer if not already running
			s.snapshotTicker = time.AfterFunc(time.Second, func() {
				s.mutex.Lock()
				defer s.mutex.Unlock()
				err := s.writeSnapshotBatch()
				if err != nil {
					panic("Failed to write snapshot batch")
				}
				s.messagesBuffer = []message.Message{}
				s.snapshotTicker.Stop()
				s.snapshotTicker = nil
			})
			return nil
		} else {
			return nil
		}