Fix reference resolution for YAML and JSON strings

[osteel]

Summary

This PR fixes an issue introduced with #52 where references in OpenAPI definitions as JSON or YAML strings weren't resolved properly anymore.

Explanation

Fixes #53.

This package previously used OpenAPI PSR-7 Message Validator's factories to create OpenApi spec objects, which also resolved references in case of definition passed as a string (see JsonFactory for instance).

When moving away from these factories to introduce support for URLs, manual reference resolution wasn't ported over.

Checklist

• I have provided a summary and an explanation
• I have reviewed the PR myself and left comments to provide context
• I have covered the changes with tests as appropriate
• I have made sure static analysis and other checks are successful

[osteel]

ℹ️ Run these checks with the minimum supported PHP version

[osteel]

Hey @dafeder, as a sanity check before I merge this, would you mind loading this branch in your app and make sure that it fixes your use case please?

   "require-dev": {
        // ...
        "osteel/openapi-httpfoundation-testing": "dev-bugfix/reference",
        // ...
    },

[dafeder]

Yep, it works!

https://github.com/dafeder/osteel-openapi-test/actions/runs/19825860641/job/56798933904

[osteel]

@dafeder excellent! Thanks for checking. Will merge and release shortly