Column gaps set to "columnWidth" do not work with nested grids

[jacobsfletch]

getColGap is fired in the global grid settings provider, and uses the cols from props. But, nested grids trim cols from the grid as they nest. This means stylesheets need to be injected at every grid, instead of the top-level settings provider, so they can read available cols from context when they are generated.

This would bloat the html, though. So alternatively, we should potentially deprecate columnWidth until css natively supports Subgrid.