Evaluate new rules in ESLint 9

[jattasNI]

Describe the issue

When we implemented #155 we made some effort to avoid introducing rules that were stricter than our existing ruleset to try to reduce churn on clients uptaking the new version. Similar to #134 we should circle back to see if there are any rules that we disabled that we want to enable.

Step 1 is figuring out how to see a list of those rules. Perhaps scanning ESLint's changelogs and blog posts? Maybe a good subset to start with would be ensuring we enable the "recommended" rules (or have good reasons to disable them).