Feature request: mpif08 github action on pull request

[hkershaw-brown]

Use case

We currently test nompi and mpi for pull requests using github actions.
https://github.com/NCAR/DART/blob/main/.github/workflows/action_on_pull_request.yml

job 1: no mpi

job 2: mpi

This feature request is for
New job 3: mpif08

Is your feature request related to a problem?

Increasing use of mpi_f08
This is an option you can (will be able to) compile dart with (#562) it would be good to catch when code changes break mpi or mpif08.
It is easy to miss changes in mpi/null/mpif08 because we have three very similar files - good candidate for a github action.

Describe your preferred solution

Add a job3 which builds with mpif08

• runs simultaneously with Job 1 & Job 2 so does not add time to the pull request checks.
• use-mpi is a boolean at the moment. This will need changing because we now have 3 mpi options.
• will need to check that the dart dependencies container can run mpif08. If not, we'll need a new container.

Describe any alternatives you have considered

Testing by hand, but I've already failed at that (see https://github.com/NCAR/DART/actions/runs/6617835818/job/17974993187)

[hkershaw-brown]

Also an observation converter - add as separate issue?