acc: add gron.py and update some scripts to use that (#4482)

## Changes
Add gron.py inspired by https://github.com/tomnomnom/gron

## Why
Simpler grepping of json, simpler to write than jq.

I need this for #4479 where
terraform & direct payload starts to differ in update due to more
defaults added to testserver & terraform persisting those in state while
direct does not.

Author: denik