CI: Check OCaml formatting

Description / Motivation

• Fixes OCaml formatting
• Checks formatter in the CI
• Makes it possible to run web pipelines
• Adds missing conf-npm package

I can clean up the history, just tell me how you want it.

How to Test the MR Manually

Checklist

• Update CHANGES.md. No need to document changes to documentation and tests.
• Make sure all new values, types etc. are documented in .mli files and that the generated documentation looks ok.
• Add tests in test/, if relevant.