Add the generated TTF files from font-liberation-ttf

This was done using the pkgsrc package.
The build is simple enough that we can add our own generation target, but
duplicating the generation logic will probably make updates annoying.

Initial import of font-liberation-ttf version 2.1.1

These are a set of 3 fonts that are metric-compatible with the most commonly
used Microsoft Windows fonts.

This is a fork of the ChromeOS core fonts that is maintained by RedHat.