Add x11-fonts/gnome-font-sampler

The easiest way to pick the right font for the job.

Features:

• View as many or as few fonts at once as you like
• Choose font size, text color, background color, bold, italics, underline, and example text used
• Double-click adds/removes a font (depending on which list you do it in)

PR: ports/75697
Submitted by: Jean-Yves Lefort <jylefort@brutele.be>