Throw a CalledProcessError not a ErrorException when run gives a nonzero exit status

[oxinabox]

When running a command returns a non-zero exit status,
currently the error function is called, which throws an ErrorException:

julia/base/process.jl

Line 693 in f9f11a3

error("failed process: ", proc, " [", proc.exitcode, "]")

That is not great. It is not a very nice exception to catch since the type doesn't tell us anything about the cause.

I am of the belief that error should not be being uses in Base/stdlib or indeed even in packages (past the prototyping stage).
It is a convenience to users, and should be used in hacky little scripts,
without error handling, where to error means to crash out.

Lets throw a real error.
Python uses CalledProcessError.
That is as good a name as any.

[samoconnor]

🚲🏚: SubprocessError

[StefanKarpinski]

SubprocessError is a good name. +1

[oxinabox]

I closed this in #27900