Convert Symfony "form" controllers to "JSON API" validation

We have an enterprise Symfony app that has approx 300 form handlers.
Each of these creates a "Symfony Form" object to validate the input.

We always post JSON input and the current validation implementation is too complex.
We want to convert these to just use the simpler "Symfony Validator" component.

For each of the ~300 forms:
1. Convert the Symfony Form definition to a simpler "Symfony Validator"
2. Update the controller to remove try/catch blocks
3. Update the Functional Tests to make sure it validator tests pass with the simpler "error" JSON response
4. Check that the updated controller still works when you submit the form from our User Interface