epic: Add support for rowname_col= and groupname_col= in LaTeX tables #783
Description
Recently, HTML output tables received expanded support in GT's rowname_col= and groupname_col= parameters. They now both work well separately and when combined. LaTeX doesn't have the same level of support so this epic would address that by fully supporting those parameters and providing LaTeX output tables that look good with those structuring options.
Addresses: #771