Copy AccessibilityPolicy definition into layoutlib

Commit 24c9045 (Change I11f1580c) introduced a new interface in
AccessibilityManager. This copies the definition of this interface in
the AccessibilityManager.java file inside layoutlib.

Test: layoutlib tests
Change-Id: I02e8d9ae6a81302a0fcdc2442bb9575fc331e4fe
1 file changed