base

Migrate Resources.java to use ICU4j drectly.

This change means that NativePluralRules can be removed in its entirety
because this is the only usage of that class.

Using a small benchmark from the NativePluralResources test, ICU4c code
takes 38.6 us and ICU4j code takes 49.2us to execute.

Change-Id: I5dbf643807c024a9c9c0f1292363fa8e39db965a