As uiautomator2 uses apk for instrumented tests this allows for distinguishing
between a normal application apk and a uiauto test apk based on the apks package
name.
Added a workload type to handle workloads that have both an APK with an
application and associated automation JAR. Added benchmarkpi
implementation using using the new workload.
Changing the way target descriptions work from a static mapping to
something that is dynamically generated and is extensible via plugins.
Also moving core target implementation stuff under "framework".
