Merge "Replace LanguageTag.isLanguage with public API" am: 1db88034cc

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1531679

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I71a9d46ed0a2edb33bcd0d631b09ee04bc0e66f6