Extend Error message type for better support of i18next

[romankoho]

The error message type is limited to being a string.
This makes things complicated when it comes to localization of error messages in combination with resolvers and form libraries like react-hook-form.

There was basically the same discussion in the yup repository:
https://github.com/orgs/react-hook-form/discussions/3808#discussioncomment-2150621

@balzdur summarized it pretty well.

there are these two issues:

• since RHF use some memoization on error messages, translation isn't recomputed after a "change locale event"

• every schema is computed from a hook that use the useTranslate hook under the hood (not very suitable since the ideal solution would be to declare schema outside the React lifecycle)

The goal would be to do the translation at the very last moment when it comes to rendering / declaring the JSX

export interface $ZodErrorMap<T extends $ZodIssueBase = $ZodIssue> {
    (issue: $ZodRawIssue<T>): {
        message: string |  {key:string; values?: object};         // extend message type
    } | string | undefined | null;
}