[Bug]: IgcGridToolbarActions - Field name instead of header caption is exported to csv if a column is grouped

[mkamiishi]

Which component(s) are affected?

Other/unknown (please specify in the description)

Description

IgcGrid has a built-in exporting feature.
When a grid containing a grouped column is exported to csv, field name instead of header caption is exported.

Reproduction

1. Go to the sample https://codesandbox.io/p/devbox/heuristic-williamson-q56s96?workspaceId=ws_Wca1rSR5QWnYWuPzcJ6uNq
2. Click "EXPORT" button on the top right corner and select "Export to CSV" from the dropdown.
3. Observe the exported csv file.

Workaround

You may set the parent property of the group columns to null in IgcGridToolbarExporter's exportStarted event and then restore the values in exportEnded event.
https://codesandbox.io/p/devbox/mystifying-mestorf-ysfggs?workspaceId=ws_Wca1rSR5QWnYWuPzcJ6uNq

Is this a regression?

No or unsure. This never worker, or I haven't tried before.

Affected versions

Failing in 6.2.0

Browser/OS/Node environment

Browser:Chrome 141.0.7390.123

[mkamiishi]

This is reproducible with IgxGrid as well > IgniteUI/igniteui-angular#16417