fix(Dataspreadsheet): add callback function for after drag/drop ends

[AustinGitHub]

Closes https://github.com/carbon-design-system/ibm-products/issues/5620

What did you change?

I added a callback method so user can know what new column headers are after drag/drop is done

How did you test and verify your work?

Storybook

https://github.com/carbon-design-system/ibm-products/assets/10100397/00c0e6d4-42de-4b5d-aaed-fb34c6bc7b99