treewide: Replace transfig with fig2dev
Reasons:
- transfig never get upstream update since it was added to nixpkgs 2006,
according to [fig2dev Debian changelog][1], upstream maintainership
was taken over at 2016, and renamed to fig2dev.
- [Debian][2], [ArchLinux][3], [HomeBrew][4] all use fig2dev to replace
transfig.
- transfig builds [failed][5] on aarch64-darwin, fig2dev builds fine.
- One less package to maintain.
[1]: https://salsa.debian.org/debian/fig2dev/-/blob/debian/1%253.2.6_beta-1/debian/changelog
[2]: https://packages.debian.org/bullseye/transfig
[3]: https://archlinux.org/packages/community/x86_64/fig2dev/
[4]: https://formulae.brew.sh/formula/fig2dev
[5]: https://hydra.nixos.org/build/163404782/nixlog/2
e8f3914985