[why]
We do not have a preview for the Symbols Only font.
The Symbols Only font appears two times (with 1000 and with 2048 EM).
[how]
Remove one of the occurences of NerdFontSymbolsOnly in the fonts.json.
The font matrix (for CI) still works, and we get only one entry in the
fonts list on the gh-pages.
Change the entry details accordingly.
Create special svg template that includes lots of symbols.
Change the destination filename to be imagePreviewFont instead of the
patchedName + "Nerd Font". The website (gh-pages) expects the former
file names.
Signed-off-by: Fini Jastrow <ulf.fini.jastrow@desy.de>
