feat(sceptre.py): move YAML rendering to configure stage #54
Description
Presently, the YAML configs for OPALRT and RTDS simulators are rendered in the pre_start stage in sceptre.py. Ideally, this should be done in the configure stage instead, which would enable users to manually verify (or change) the configs without starting the experiment.
Implementation should be relatively straightforward, but there are a few dependencies/gotchas I need to workout, so thus a issue to track this.
Originally posted by @glattercj in #53 (comment)