Write tests for all remaining scripts and lib files

[kb0rg]

This is an epic, and will be split off into smaller tasks.

We now have automated tests running in Github Actions, but tests have not been written for the majority of our codebase.

We aim to improve coverage incrementally as we add new features, but we should also try to tackle adding tests for some of the existing scripts and utilities. The goal here should be to achieve coverage for things whose breakage will be hugely problematic, while not spending too many extra cycles on the scripts that are nice-to-haves. We should still seek to keep these working, but that is best served by being able to quickly update them, and they generally don't have secondary dependencies that might cause unexpected breakage due to a change elsewhere.

Library files that need coverage:

• config
• zoom

Script files that need coverage:

• access-limit
• admin
• gif-locker
• github-auth
• github
• health-check
• passport-init
• remin
• sandbox
• schedule
• suggest
• zoom