Add periodic workflow for generation reference frames

[scotts]

We have a script, generate_reference_resources.sh, that we run when we are adding new reference frames for testing. We should add a workflow to periodically execute this script. The workflow would not change the checked-in reference frames. Rather, the point is for us to discover early if somehow we broke the script.

Adding new reference frames is rare, and as a result we only need to rarely run the script. It's easy for something to go wrong with the script and we only realize it months later.