This is essentially a CLI wrapper around the hcldec package, accepting a
decoding specification via a HCL-based language and using it to translate
input HCL files into JSON values while performing basic structural and
type validation of the input files.
This is a super-invasive update since the "zcl" package in particular
is referenced all over.
There are probably still a few zcl references hanging around in comments,
etc but this takes care of most of it.
The main "zcl" package requires a bit more care because of how many
callers it has and because of its two subpackages, so we'll take care
of that one separately.
This applies the simple native syntax reformatting function to one or
more files. It does not support JSON or any other syntax.
Calling applications might provide their own versions of this that e.g.
can format an entire directory by matching on filename patterns, but
this serves as an example and a utility for single files.
