CI / CD Setup

Investigate Forest's CI / CD and implement what makes sense from the list:

- [ ] audit (security vulnerabilities)
- [ ] taplo (TOML files linting)
- [ ] spellcheck
- [ ] mdbook-linkcheck (checks for broken links)
- [ ] udeps (unused dependencies)
- [ ] nextest (drop-in replacement for test runner, makes it easy to spot bottlenecks and runs faster than the standard tool)
- [ ] quickinstall (faster installation for well-known cargo plugins)
- [ ] caching mechanisms
- [ ] shellcheck (not Rust-specific but it's cheap to add it and most projects end up with some shell scripts anyway)

On top of this, snatching the [license script](https://github.com/ChainSafe/forest/blob/main/scripts/add_license.sh) might be helpful.