locales should inherit from defined parent locales when available

[patch]

Right now, the inheritance works like zh-Hant-MO → zh-Hant → zh → root, but Part 1 Core §4.1.1 Parent Locales defines exceptions in the LDML for different parents.

For example:

 <parentLocale parent="zh_Hant_HK" locales="zh-Hant-MO"/>

This would modify the inheritance to zh-Hant-MO → zh-Hant-HK → zh-Hant → zh → root.

Others are defined with a parent of root to skip normal steps altogether. The most notable problem with the current inheritance is that es-US (US Spanish), es-MX (Mexican Spanish), es-CR (Costa Rican Spanish), etc., inherit directly from es (European Spanish) instead of es-419 (Latin American Spanish).