Allow overriding validation message Locale via configuration

[botond012]

Description

Currently validation messages seem to depend on the JVM/default Locale.

In my case the application locale is Hungarian (hu), so validation messages are returned in Hungarian. This is not always desired: I may want the application locale to stay Hungarian, but validation errors to be returned in English or another specific language.

It would be useful to override the locale used for validation messages through configuration.

Expected behavior

Provide an API such as:

OpenApiValidator validator = new OpenApiValidator();
validator.setLocale(Locale.ENGLISH);