Changing view configuration causes the expanded/collapsed state of groups to be reset

Bug Report

Steps to Reproduce:

1. Look at the DataGrid example on https://perspective.finos.org/
2. Collapse a few groups by clicking the "-" button
3. Change something about the view, like adding an additional column
4. Notice that all the previously collapsed groups are now expanded again, causing the information that you were viewing to be pushed out of view

Expected Result:

The expanded/collapsed state of rows should be maintained when changing other state of the view, such as the set of columns or the sort order.

Actual Result:

The expanded/collapsed state of rows is not maintained when changing any state of the view.

Environment:

Not environment specific

Additional Context:

N/A