Hook up hibernation eligibility to exemption toggle

Use hibernation eligibility API to determine whether toggle should be
enabled or disabled for an app. For apps that are already exempt from
hibernation by the system, the toggle is disabled and unchecked.

Bug: 200087723
Test: manual
Test: atest AppHibernationIntegrationTest
Change-Id: I36a1eafc2bb90a92bcbdc4bf32041426d6377fd4