Remove manual steps from the accessibility CTS tests.

1. Added a host side test that serves as a runer for the CTS
   test which are instrumentation tests. The runner is responsible
   for installing all needed packages, enabling accessibility
   and the delegating accessibility service via shell commands,
   running the instrumentation tests on the device, and cleaning up.
   This test is pretty much a driver for running the remote tests.
   To fit the current state of the CTS test framework the driver
   has to declare as empty test method all remotely run tests so
   description of these tests to be added in the CTS test description
   XML because CTS allows only reporting results of declared tests.

2. Updated the JarHost test to use the same class loader for each
   method of a test it ruts to enable sharing static state between
   test methods - this is useful to avoid doing expensive operations
   before every test.

bug:5946699

Change-Id: I41f4016c386c16c2ce517641f5b18045f67f46f1
8 files changed