feat: add transformObject hook

[samchungy]

I've kept it similar to the transform hook to allow for additional parameters should we wish to add them in the future.

Resolves #736

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[mcollina]

lgtm