Grouped column header does not freeze when scrolling horizontally

[telenord]

Describe the bug

Grouped column header didn't freeze despite it has property frozen=true

To Reproduce

Link to code example:
https://codesandbox.io/p/sandbox/rdg-bug-frozen-column-qy7hyh

Expected behavior

Grouped column header is frozen and moves with the child columns

Environment

• react-data-grid version: 7.0.0-beta.44
• react/react-dom version: 18.2

Additional context

[amanmahajan7]

This is not supported at the moment

[ZachSARAO]

I would be interested in being able to freeze N rows. Would this be hard to implement?