Packages the telega-server binary and adds the required mode into
Emacs.
Unread message count is displayed in the modeline, which is neat.
Probably need to figure out some key bindings for this.
This enables usage of __dispatch.sh from anywhere, even outside of the
depot.
Specifically this means I can add `~/depot/bin` to my $PATH and all
the registered tools work from anywhere.
Instead of exposing the entire package tree from nixpkgs, whitelist
individual packages explicitly so that they show up in
`pkgs.third_party`.
This makes it much easier to control external dependencies used by my
projects.
Bonus: It even includes a working `third_party.callPackage` with only
the whitelisted packages!