SCC-3986: Node20

[nonword]

Update app to use Node 20.

• Added qa and prod encrypted config to ./config/ and updated app to decrypt it on startup
• Updated all dependencies (except vulnerable sub-dependencies of other nypl modules, for which I created tickets)
• Removed many vulnerable dependencies that could be removed with minor app changes (including removing some unused data files)
• Removed invalidated sections of README
• Rebuilt many fixtures
• Linting
• GH actions for testing and deploying from the Node 20 QA release branch
• Removed .travis because gh-actions covers things (and travis is failing nvm i for Node20 for some reason)

[charmingduchess]

Hey Paul! I'm going to take a closer look at this later, but I'm wondering for starters if we can git ignore the fixtures moving forward. I can sort of see why we'd want them committed, but I imagine the tests should theoretically pass whether the fixtures are exactly the same or not.

[nonword]

This has been approved, but we're not ready to merge this to main yet. This node20 work now lives in release branch qa-node20 for testing.