Require that the caller has INTERACT_ACROSS_USERS in order to retrieve

home tasks of other users.

This prevents users from observing home tasks of other users on the device.

bug: 140274903
Test: cts-tradefed run cts-dev -m CtsPermissionTestCases -t android.permission.cts.NoActivityRelatedPermissionTest#testGetTask
cts-tradefed run cts-dev -m CtsWindowManagerDeviceTestCases
cts-tradefed run cts-dev -m CtsAppTestCases
Change-Id: Ia5fdb1ba1ab7d9ec27d1afbb3a359b454c7075c0