observation converter build GitHub action pull requst

[hkershaw-brown]

Use case

What are you trying to accomplish? Sometimes there may already be a way to do what you need.
We have a "build and run" GitHub workflow to check that pull requests have not broken DART (via lorenz_96).

Is your feature request related to a problem?

The current PR workflows do not exercise buildconvfunctions.sh.
It is easy to make changes that pass the lorenz_96 tests but break observation converters, and not realize this.

The "build everything" workflow does catch converter build problems because it builds every executable in DART, but it cannot be run on forks (#686). As a result, contributors do not get feedback if/when their PR breaks converter builds.

Describe your preferred solution

Add a workflow that runs on pull requests and builds and runs an observation converter.

• Run in parallel with the existing lorenz_96 PR workflows
• Take less time than the documentation build
• No MPI requirements (MPI, no-MPI, mpif08 coverage already comes from lorenz_96 workflow)
• Converter with no external dependencies. I believe this is sufficient for “this change broke converter builds" while allowing local debugging without needing rttov, hdf4, or whatever the various converters have as dependencies.

You could use the containers with full observation converter dependencies (see run_all_quickbuilds.yml for pulling the container), but again many observation converter fails could send someone down a rabbit hole debugging.

Describe any alternatives you have considered

Full test suite with coverage run on pull requests, but we are a ways away from that.