We can easily construct netstrings from nix strings, which is super
helpful to inject proper structured data into execline scripts.
Change-Id: Ie8bffed285896223db83652eaea868ece43592b9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3265
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>