Add Validation Error Mapping / Normalizer

[joshuatz]

A common need across different Django-based projects is consolidating and normalizing error messages. For example, the base Django internals, Django-Rest-Framework (DRF), and Django-Ninja - all handle how they format and raise validation related errors just slightly different enough to require some standard boilerplate code each time.

Ideally, this feature would be exposed as some sort of normalizer function that can take a union of (pseudo-types) DRFValidationError | StdValidationError | |NinjaValidationError | PydanticCoreValidationError | ...