pack_qwk.cpp

Before now, the archive formats/types (e.g. for creating QWK/REP packets or
temp file download archives) supported by libarchive have been *hard-coded* in
Synchronet to "zip, 7z, tgz", but if you really want to support the creation
of more archive formats using the internal (libarchive) support in Synchronet,
and your system supports it (e.g. confirmed using archive.js), you can add
those types to this list or remove any that are problematic.

This list does not impact the archive types that can be viewed or extracted
using libarchive.