So that helper scripts can be easily sourced in interactive shell
configuration. `autojump` package was already present and had the same
requirements for findind a `share` folders, so I took an inspiration
there.
I beleive this is a better alternative to:
- https://github.com/NixOS/nixpkgs/pull/25080
- https://github.com/NixOS/nixpkgs/pull/27058
Replacing `$out/share/shell` with `$bin/share/fzf` was necessary to
prevent dependency loop in produced derivations.
This gives some basics on configuring Emacs within Nix. The
configuration is fairly long just to give a good idea of what’s going
on. I can trim out some of it if it’s not necessary. Note that there
is already a section for Emacs in the NixOS manual. However, this is
aimed at avoiding using modules altogether to make things easier for
non-NixOS users. This configuration should work on NixOS anyway,
however.
Fixes #24243
Fixes #19956
