Introduce ImeTargetVisibilityPolicy

This class provides ime target visibility
utility functions from IMMS to WM as:
-. update ime screenshot
-. update ime parent

This change only build the class and no module
rely on it so it shouldn't have behavior changes.

Bug: 258048231
Test: atest WmTests:ZOrderingTests#testImeScreenshotLayer
Change-Id: Ie567ba578dca65be0a9a11d9a4aa27a13fe69900