Hi 
I think this would be trickier than expected.
If you create an HTML table in your post, and someone quotes your table, it’s converted into Markdown which doesn’t support rowspan and colspan.
I suspect there would be other issues I didn’t think about.
It’s not exactly the same, but you can wrap your table with [wrap] tags
See: Customize posts' contents with your own styles
But you won’t be able to have data- attributes inside an HTML table (for example, to customize specific rows or cells).
edit: if your table uses Markdown instead of HTML, you can insert spans with data- attributes like this:
|Column 1 | Column 2|
|--- | ---|
|<span data-thing>test</span> | test|
|test | test|
But they will be removed if someone quotes or copy-paste your table.