Ability to validate against the normalized input

Useful in the scenario when you want to allow

```
# 10 digits are extremely common in the US
555 555 5555
```
even though it would fail Phony.plausible?().

After normalizing for “US”, this would pass.
i.e. Phony.plausible?(PhonyRails.normalize_number)

Usage looks like:

```ruby
validates_plausible_phone :phone_number, normalized_country_code: 'US'
```