Add linting scripts

[gcpreston]

In creating a PR as part of the erlang -> JS porting initiative, I looked for some kind of npm run lint command, since it's clear the JS code is consistently formatted, but in finding none, I just did my best, only for it to fail CI.

This PR adds two npm scripts to remedy the issue: lint and lint:fix.

• lint will run the prettier command previously defined in ci.yml
• lint:fix will run the same command with --write to fix any issues found

ci.yml has also been changed to call npm run lint, so that the command is not defined in two separate places.