This is a writer, similar to `pkgs.writeBashScript` or
`pkgs.writers.writePython3`.
The difference is that we can correctly write all execline scripts by
using nix lists of lists, so the user doesn’t have to care about
escaping arguments (like they have to in bash scripts with
`lib.escapeShellArg` for example).
Change-Id: I2f2874cf61170ddca07b89b692f762725f4a75dc
Reviewed-on: https://cl.tvl.fyi/c/depot/+/625
Reviewed-by: Kane York <rikingcoding@gmail.com>
Reviewed-by: tazjin <mail@tazj.in>
