Implement ILibCountry class

[seonmiJin]

Checklist

The following lists affects Pub Points on pub.dev when the package is published.

• Passed the all tests.
• Verified that the example app works.
• Executed the dart format command.
• Added the API description is added if necessary.

Description

• Implement ILibCountry class
  • This class encode information about country name.
• Update ilib-init.js to include Country featrue from the iLib
• Update the [locale].js file to include Country locale JSON date from the iLIb
• Usage:

final ILibCountry ctry = ILibCountry(locale: 'ko-KR');
ctry.getName('TR');
// '튀르키예'
ctry.getCode('튀르키예');
// 'TR'