Phone number formatting does not comply with libphonenumber specification

[fpbouchard]

As is documented here, to prevent data deduplication, format rules are not copied to all NANPA countries, and the mainCountryForCode attribute is set for countries that share the same calling code.

I am willing to submit a PR that fixes this. From my understanding of the code, my two choices would be to duplicate the formats in metadata_formats_by_iso_code.dart, but increasing the file by ~1200 lines, or refactor PhoneMetadataFormat so that it can either refer to another IsoCode or contain a list of PhoneMetadatFormat.

I prefer the second approach, but I ignore if the generated files have to remain stable or if they can be changed.

Let me know!

[cedvdb]

Hello @fpbouchard Thanks for the detailed issue and research. I'm with you for the second approach. Since the metadata is currently public, this would still need a major semver upgrade.