Add run.sh script to project

[jonaharagon]

Changes proposed in this PR:

• Adds a run.sh script for running the website locally. The switch to environment variables in Remove per-language config files #2513 probably made it harder to run translated copies locally, now you can: ./run.sh --lang=fr
• Switches from git committers plugin to git authors plugin, because the git committers plugin wasn't caching things right and I wasn't really a fan of the GitHub-specific nature of it anyways (this is the plugin that adds authors to each page's footer FYI)
• Adds .mailmap to merge multiple git identities from authors in git log / git blame - I added the most obvious suspects I could find at a glance, but we should strive to add every person who commits with multiple Git identities over time to this file.

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[jonaharagon]

fyi mailmap is also needed for https://timvink.github.io/mkdocs-git-authors-plugin/mailmap.html it isn't just for git log

[privacyguides-bot]

This pull request has been mentioned on Privacy Guides. There might be relevant details there:

https://discuss.privacyguides.net/t/2024-04-11/17822/1