errors, child_process: use more internal/errors codes
Converts more (I believe this is all that is remaining?) of child_process
to new-errors
-land. Most of this diff is straight copy and replace, so I don't think it's too intimidating. There are a few TODOs left in this PR on purpose that require some discussion, so I would appreciate any feedback on those.
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
commit message follows commit guidelines
Affected core subsystem(s)
errors, child_process