Enable adding new validators by defining spring beans to complement the default Validator

[taefi]

Describe your motivation

At the moment, Hilla looks for a bean of type Validator, and if nothing found, it falls back the default from Jakarta API.
Most of the times, the defaults are needed, and the user wants to add some custom validators on top. Hilla can make it easier for the users to define as many custom validators as they want to complement the defaults, not to replace it.

Describe the solution you'd like

The main motivation of this enhancement issue is to the enable users introducing as many Validator beans to use them on top of the default from Jakarta API.

Then, if possible, the framework can expect an optional bean of type ValidatorFactory to enable users for completely opting out from the default, and introduce their own universal Validator.

Describe alternatives you've considered

No response

Additional context

No response

[cromoteca]

jakarta.validation.Validator does not support customization. It can be replaced with a custom implementation, that could wrap the default. This should be already possible in Hilla, by creating a Spring Bean that implements Validator.

[taefi]

I was mostly picturing it as looking up all the Validator beans, and validate parameters against all of them (including the default from Jakarta).

[cromoteca]

Implementing a Validator is quite unfriendly: https://jakarta.ee/specifications/bean-validation/3.1/apidocs/jakarta/validation/validator

[platosha]

We need some proposal here to help implementing custom Validator that delegates to the default one.