[Feature] reference variable

[armored-glitch]

MaxKB Version

2.3.0

Please describe your needs or suggestions for improvements

这个地方的引用变量得提前用变量赋值组件转成json ，后面表单的下拉框才可以展示呀 多场景下是没办法使用的

Please describe the solution you suggest

No response

Additional Information

No response