1. Added flags to the search method to specify whether to match text or
content description or both.
2. Added test case for the seach by content description.
3. Updated the code in AccessibilityManager service to reflect the latest
changes there so test automation service works - this is the fake
service used for UI automation.
Change-Id: I14a6779a920ff0430e78947ea5aaf876c2e66076