Initial implementation of Java-based broadcast radio service.

It provides only limited amount of service, without actual interaction
with HAL.

Added config.enable_java_radio switch to use Java-based service instead
of native. Added FEATURE_RADIO to PackageManager.

Bug: b/36863239
Test: Instrumentation, manual (Kitchen Sink)

Change-Id: I01139d326893c0a437c60cc35d6e5b005da35231