Use language tags to store Configuration's locale list.

Instead of storing each Locale within a Configuration object's locale
list by its language, country, variant, and script to proto, store the
entire locale list by its language tags representation which accurately
describes each locale.

Bug: 140197723
Test: atest ConfigurationTest
Test: atest UsageStatsDatabaseTest
Test: manually with bad data
Change-Id: Id0e63ae4a7be578d1e93838b371320f86a787e0e