[feature] provide method by which to attach additional metadata to the returned ValidationError

#### Context

```
❯ npm explain joi && node --version && uname -a
joi@17.6.0
v16.14.2
Darwin 5c52309d33e3 20.6.0 Darwin Kernel Version 20.6.0: Tue Apr 19 21:04:45 PDT 2022; root:xnu-7195.141.29~1/RELEASE_X86_64 x86_64 i386 Darwin
```

#### What problem are you trying to solve?

I need some kind of parent label that can be retrieved from the Validation Error Message. We have essentially `User.firstName` throwing an undefined (because required) error. Unfortunately `ValidationError` only provides `firstName` in the metadata, and there is no way for me to see that the root object has label `User`.

I need some way to supply to the error handler via the ValidationError the meta data `User`. I've tried `label`, `meta`, `notes`, `error()` etc. None of it carries the data, and most of it doesn't even show up in the validation error (why does it exist?).

#### Do you have a new or modified API suggestion to solve the problem?

just put things like meta and parent label, etc in the validation error details.