Implement `Intl.DisplayNames` in Dart's `intl` library

[kyle-seongwoo-jun]

I would like to request the implementation of Intl.DisplayNames in Dart's intl library, similar to the Intl.DisplayNames in JavaScript. This would allow Dart developers to easily access locale-specific names for languages and regions, and provide a more consistent and convenient way to work with locale information.

Having access to a standard repository of locale information, such as CLDR, is essential for building globalized software systems that support multiple languages and locales. The Intl.DisplayNames feature in JavaScript provides a convenient and flexible way to access this information, and I believe that a similar feature in Dart would be a valuable addition to the intl library.

Thank you for your consideration.