[EuiDataGrid] Allow custom class name for EuiDataGridHeaderCell

[walterra]

This relates to this Kibana issue: elastic/kibana#110053

With a higher header cell, the sorting icon will still be vertically aligned which we'd like to change in this case. Right now we have to override EUI classes which we'd like to avoid.

[github-actions]

👋 Hey there. This issue hasn't had any activity for 180 days. We'll automatically close it if that trend continues for another week. If you feel this issue is still valid and needs attention please let us know with a comment.

[JasonStoltz]

@cee-chen Can you link your current work here?

[cee-chen]

Once #6609 lands, you'll be able to accomplish this with the displayHeaderCellProps property in columns:

// Example css
.yourClass {
  vertical-align: top; // or whatever
}

// Example column
const columns = [
  {
    id: 'someColumn',
    display: <>Column <EuiIcon type="dot" /></>,
    displayHeaderCellProps: { className: 'yourClass' },
    // etc.
  },
];

// Example data grid
<EuiDataGrid
  columns={columns}
  // etc.
/>