Figure out how to test that the column selection dialog closes

[brianlove]

The column selection dialog test failed during #154 - despite various methods working perfectly on my local machine, they failed when run with GitHub Actions.

To temporarily resolve the issue I commented out the lines associated with the modal test in 5a863d5. Figure out how to check that the dialog has closed in a way that works both locally and on GitHub

[brianlove]

This was resolved in #156 (specifically cbb30a6):

      let dialogRemoved = waitForElementToBeRemoved(screen.getByRole('dialog'));
      await user.click(getByRole(dialog, 'button', { name: 'Apply' }));
      await dialogRemoved;