statsd side implementation of Stats HAL

This change implements server-side of Stats HAL in statsd to be able to
receive loggings and parse them into LogEvent event before passing them to
StatsLogProcessor.

Bug: 114316519
Test: verified that statshal exists by calling 'adb shell lshal'
Change-Id: I43e7415a2d28e20af872049100cd6f2627cf3c02
7 files changed