This libpkg plugin implements support for handling AppStream metadata.

To enable it make sure it is installed into PKG_PLUGINS_DIR (which is usually
"/usr/local/lib/pkg/") and is listed in the PLUGINS entry of pkg.conf

The plugin fetches a file named AppStreamComponents.xml.gz which is expected to
be present at the repository root. It then places it into
/var/lib/swcatalog/xml/<repository name>-Components.xml.gz location which is
a well-known place for the AppStream-enabled software.