Add option to set "First Column" as header

Attached patch adds a First Column choice for header.

Makes sense to me, thanks @possibri! Tested and reviewed your patch @jgjg, and looks good from my end. I opened an MR applying your patch.

The available options are by column or both to improve accessibility, HTML tables with only row headers aren't described correctly by some screen readers, tables should always include column headers, even if you are using row headers. This is generally the recommended approach and considered a best practice.

I'm changing the status of this ticket to "won't fix" for now, but feel free to re open it again if you have a compelling reason for including it.