Refactor embedded window handling in AccessibilityWindowManager

Embedded windows are maintained globally, not per display.
This moves isEmbeddedHierarchyWindowsLocked method from
DisplayWindowManager to A11yWindowManager.

Bug: 322444245
Test: CtsAccessibilityServiceTestCases, AccessibilityWindowManagerTest
Change-Id: I5e4f1684439dc12035672c4ae8a328a8113b600c
2 files changed