removeCountryCodeFromMask results in incorrect phone mask for national numbers

[woelmer]

Calling this text formatter:

LibPhonenumberTextFormatter( country: usCountry, PhoneNumberFormat.national)

Will result in the following mask "0) 000-0000"
It should be "(000) 000-0000"

There are a couple problems:

1. input_formatter.dart line 28: removeCountryCodeFromMask gets set to true even though the phone number is a national number and the inputContainsCountryCode is false.

2. Once removeCountryCodeFromMask is true country_data.dart line 188 will remove three characters from the beginning of the national mask therefore chopping off the area code portion of the national phone number mask.

[mockturtl]

@acoutts This bug is still present in 2.1.5.

In my use case, the "country picker" is a separate dropdown / bottom sheet, so the input text field will not include the "pluscode" ("national" format; inputContainsCountryCode is false).

Since the mask is "national" (already excludes the pluscode), I believe it's redundant to trim it by taking a substring.

[mockturtl]

I forked the repo to fix this issue for my use case. Feedback / PR's welcome.

fix-22-national-mask

dependency_overrides:
  flutter_libphonenumber_platform_interface: #https://github.com/acoutts/flutter_libphonenumber/issues/22
    git:
      url: https://github.com/mockturtl/flutter_libphonenumber_platform_interface
      ref: fix-22-national-mask