Add artd unit tests.
This change adds `art_artd_tests`, which contains the unit tests of
artd. The change also splits the code into artd.h/artd.cc and
artd_main.cc, where artd.h/artd.cc contains the implementation that is
unit-testable, while artd_main.cc contains the main function of the artd
binary.
Bug: 177273468
Test: m test-art-host-gtest-art_artd_tests
Test: ArtGtestsTargetChroot:ArtdTest
Ignore-AOSP-First: Will cherry-pick later.
Change-Id: I19701d7ca83f541becdcd413e740eff93d03037d
9 files changed