Initial CTS tests for Content Capture.

It's still rudimentar and only checks one scenario (a blank activity that is
launched and finished), but well, even the Universe started with a Big Bang!

Anyways, the main limitations are:

- Everything runs in one APK; we should have at least one more for the service,
  so that project can be compiled using the system SDK, while the main test
  is using hte testing SDK.
- The service is still set using Settings; we need to use a Shell command to
  override the service that's defined by framework resources.
- It's not testing other scenarios like view-level events, neither multiple
  activity changes (like paused / resumed twice)

Test: CtsContentCaptureServiceTestCases
Bug: 119638528

Change-Id: I62957b634fa5704fde64fb9975a6a69f6f35f633
12 files changed