Add a format checker before running the build

[ccarouge]

There has been an issue with a branch name that contained "+". This tripped Spack.

It would be great to have a format checker running at the creation of the PR. The checker could indicate any issue found and possibly give a preferred branch name that is compatible with Spack.

I don't think we want the action to change the branch name on GitHub directly as it would break the pull/push with the local repo. Maybe we should give instructions of the commands to run locally if the name needs to be changed. I'm not sure how much we want to hand-hold people but we will always have contributors who are new to git.