Node - #activity#clear_info

For Xmind ChatTree, the first line of the node content must be "#activity#clear_info", and then the content of the second line is the InfoItems, if there are multiple ones, use "|" to separate them, such as:
```
#activity#clear_info
{...}|{...}|{...}
```
For Python ChatTree, the first parameter of chattree.create_node() must be "#activity#clear_info", the key in the second parameter dict is "infoitem", and the value is the name of the InfoItem (str or list[str] type), such as:
```
xxx_node = chattree.create_node("#activity#clear_info", {"infoitem": ["{...}", "{...}", "{...}"]})
```
Clear the contents of related InfoItems, that is, delete the values of related InfoItems (note that the value is not assigned to None), you can also use the code in "Python Script/Function" to achieve the same effect