community/foot: restore extra terminfo files in new -extra-terminfo package

c4a2d5e7 disabled building and packaging foot's own "extra" terminfo files so that they would not conflict with the ones provided by ncurses-terminfo. This change restores those extra files as part of a new (optional) package called foot-extra-terminfo.

By default, foot will continue to use the term name "foot", and thus use the terminfos provided by ncurses-terminfo. If the user wants to use the terminfos from foot-extra-terminfo, they'll need to set term=foot-extra in their foot config.