The DataTables CSS and JS files are bundles built by the DataTables download tool at https://datatables.net/download. Consult the first few lines of each file to confirm what has been bundled and therefore what is needed by the Drill web UI, e.g.

Included libraries: jQuery UI 1.13.2, DataTables 1.12.1, Buttons 2.2.3, Column visibility 2.2.3