Support loading a config into the XLR Validator

[kharrop]

Is your feature request related to a problem? Please describe.

Currently there isn't a way to pass a config into the validator.

Describe the solution you'd like

We'd need to extend the SDK to take the config in for the validator to pass down as well as expose it to the CLI plugins. Conversely we could add a method to add to that map after the Validators been initialized.

Additional context

This was originally discussed as future work from #189