chore: enforce prettier and eslint

[mattjennings]

===:clipboard: PR Checklist :clipboard:===

• 📌 issue exists in github for these changes
• 🔬 existing tests still pass
• 🙈 code conforms to the style guide
• 📐 new tests written and passing / old tests updated with new scenario(s)
• 📄 changelog entry added (or not needed)

==================

See issue #2378

• Add prettier for code formatting
• Update eslint config to parse other parts of codebase outside of src/engine, and also remove rules that are handled by prettier
• Add husky & lint-staged to enforce formatting on git commit
• Add format step to all and all:ci scripts

I separated the commit that runs the format & lint on all files into #3015 so the config can be easily reviewed here.

Once we're happy with this, we can merge that PR into this one and ignore the commit(s) using git blame --ignore-rev to remove it from git blame history.

[eonarheim]

Nice! The CI fails as expected here ;)

[eonarheim]

LGTM

@mattjennings We expect the CI to balk at the moment because we haven't run this yet correct (at least that's what appears to be happening at the moment)

[mattjennings]

@eonarheim yup - that's in #3015. So if you approve that PR we should see the checks run & hopefully pass, then we can merge it into this PR so we can ignore the commit before merging everything altogether into main.

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