[Payment Request] Update the CurrencyStringFormatter to call the native impl.

Uses components/payments/currency_formatter.h by way of a JNI bridge.

Had to get rid of the junit tests because the implementation now require the
native libraries to be loaded.

BUG=679797
TEST=CurrencyStringFormatterTest, manual

Review-Url: https://codereview.chromium.org/2629883004
Cr-Commit-Position: refs/heads/master@{#443797}
14 files changed