Create action for payu config checks

[aidanheerdegen]

Deploying payu configurations would greatly benefit from CI checks to ensure configurations conform to some standards and avoid simple errors.

Code could be adapted from this repository which was designed to do these sorts of checks for ACCESS-OM2 experiment configurations

https://github.com/COSIMA/cleanconfig

The tests are contained here

https://github.com/COSIMA/cleanconfig/blob/master/test.py

They should be fairly self-explanatory and are mostly designed to ensure model configurations are portable and useable by everyone.

[aidanheerdegen]

It probably makes sense to retain the checks as python scripts in the repo, as there is some path checking stuff which would be a pain to do in bash.

Edit: but this would require a python install ...

[aidanheerdegen]

I would also like to add checks to make sure we have

reproduce:
   exe: True
   input: True

set in config.yaml