在Select选项改变时，获取改变前后的值 #3814
Description
Is there an existing issue for this?
- I have searched the existing issues
Is your feature request related to a problem? Please describe the problem.
需要在改变选项时，同步更新一些其他的数据，但是 OnSelectedItemChanged 无法获取到修改前的值，使用 OnBeforeSelectedItemChange 又会有弹窗，如果在这里更新，弹窗中选择取消就不对了。
Describe the solution you'd like
OnSelectedItemChanged 中能获取到改变前的值，或者 OnBeforeSelectedItemChange 能设置不弹窗。
Additional context
No response