Running pre-commit with GitHub Actions now gives us more tests and coverage

Remove duplicate GitHub Actions for merge conflicts and trailing whitespace

Remove duplicate checks for markdownlint and yamllint from the GitHub Super-Linter

Add new custom pre-commit hook running with a shell script to sort alphabetically and uniquify codespell.txt

Add new pre-commit hook to check spelling with codespell

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

Fix spelling