Add codespell as a github action

[luzpaz]

Thanks again @luzpaz! If you can help us with adding this as an action in .github/workflows/repo-check.yml, we will appreciate it.

Originally posted by @tzanio in https://github.com/mfem/mfem/issues/3134#issuecomment-1242236631

https://github.com/codespell-project/actions-codespell

[luzpaz]

@tzanio there should be a streamlined way to do this through github, see codespell-project/actions-codespell

[tzanio]

I tried the above ☝️ quickly in #3205, but it doesn't seem to work.

@luzpaz, any ideas what is wrong?

[stale[bot]]

:warning: This issue or PR has been automatically marked as stale because it has not had any activity in the last month. If no activity occurs in the next week, it will be automatically closed. Thank you for your contributions.

[v-dobrev]

Discussion continued in #3205.