Implement ILibCaseMapper

[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 ILibCasemapper
  • It maps strings to upper or lower case. This mapping will work for any string as characters that have no case will be returned unchanged.
  • Usage:

final ILibCaseMapper mapper = ILibCaseMapper(locale: 'tr-TR');
mapper.map('ıi');
// 'Iİ'
final ILibCaseMapper mapper = ILibCaseMapper(
    locale: 'tr-TR', direction: 'tolower');
mapper.map('Iİ');
// 'ıi'