node:dragleave事件在节点内drag时频繁触发 #5780

@Aarebecca @Yanyan-Wang

node:dragleave的问题根源是，在drag到另一个节点上时，并且在节点内快速移动，就会错误的触发dragleave，很慢的移动则是正常现象🔴 ✅✅✅✅✅故此，用用其他方法实现了

stack: [],

onDragEnter(e) {
    const item = e.item;
    if (!this.dragItem || !this.isMouseDown || !item) {
      return
    }
    const self = this;
    const model = item.getModel();
    this.dropItem = item;
    self.graph.setItemState(item, "dragState", true);
    this.clearActiveState(model.id);
  },

clearActiveState(id) {
    const self = this;
    this.timer = setTimeout(() => {
      self.throttleClearActiveState(id, self);
    }, 50)
  },

  throttleClearActiveState: throttle((id, self) => {
    self.stack = Array.from(new Set([...self.stack, id]));
    if (self.stack.length > 1) {
      const prev = self.graph.findById(self.stack[0]);
      self.stack.splice(0, 1);
      if (prev) {
        self.graph.setItemState(prev, "dragState", false);
      }
    }
  }, 50,{
    trailing: true,
    leading: true
  }),