Feature Request: Give an error hint if wrong attribute case is used

This issue is a (choose one):

• Problem/bug report.
• Feature request.
• Request for support. Note: Please try to avoid submitting issues for support requests. Use Gitter instead.

Checklist before submitting:

• I've searched for an existing issue.
• I've asked my question on Gitter and have not received a satisfactory answer.
• I've included a complete bug report template. This step helps us and allows us to see the bug without trying to reproduce the problem from your description. It helps you because you will frequently detect if it's a problem specific to your project.
• The feature I'm asking for is compliant with the JSON:API spec.

Description

Choose one section below and delete the other:

Features:

If I set my attribute casing to be say camelCased, but the request comes in with attributes that are snake_cased or kebab-cased, when we throw a "param not allowed" can we instead check if the cases just mismatch and instead throw an error indicating that you may have been using the wrong case. This is something that happens occasionally especially with new engineers getting on a project, but would instantly save a bunch of frustration here and there when these bugs happen.

Start by locating the handling for a "param not allowed" error and the configuration for attribute casing. Check how camelCased, snake_cased, and kebab-cased attributes are processed, then verify that a mismatched case produces a helpful hint without changing valid JSON:API behavior.