Fix incorrect time display format in TimePicker in Chinese

[rk0cc]

1. Edit Chinese localization of time to more accurate one.
2. Add mixin that handle Locale script code is applied.
   • This problem only happened in Traditional Chinese. When time is picked, expected to display '時', not '时' which is Simplified because intl package can not recognized with script code given.
   • As a result, a mixin is deployed which convert to locale string that intl can be recognized.
     • In this case: zh_Hant_(country code) will be converted to zh_(country code). If parsed without country code like zh_Hant, it will applied with default country code which in Trad. Chinese is zh_TW.

Pre-launch Checklist

• I have updated CHANGELOG.md with my changes
• I have run "dart format ." on the project
• I have added/updated relevant documentation