add Adobe Base 14 fonts

[ashutoshvarma]

As fontconfig support is disabled in pyxpdf for now (see issue) and xpdf's font detection is pretty sloppy so I think We should at least distribute base 14 fonts in pyxpdf_data as they are not required to be embed as per PDF specification. Users can add them manually but it would be more convenient it they are included by default.

We can use free ghostscript fonts from git.ghostscript.com/urw-core35-fonts.git which are available under GNU Affero General Public License