Stops reporting identical objects as being different

[arcanis]

What's the problem this PR addresses?

The constraints engine is making a === check, so using the set method with a JS object will never match and will report an error (example here).

How did you fix it?

We now compare stringified values to check sameness. I considered using something like _.equals, but using stringify only returns true when the key are in the same order, which is important for fields like exports.

Checklist

• I have read the Contributing Guide.

• I have set the packages that need to be released for my changes to be effective.

• I will check that all automated PR checks pass before the PR gets reviewed.