Add PowerWhitelistManager.isWhitelisted.

The "XXXExceptIdle" lists and methods are expected to be a superset of
the XXX methods. That's not immediately obvious from the method names.
This effort is to clean up the naming and better document actual
behavior. As part of this, we're moving the isApplicationWhitelisted
methods to PowerWhitelistManager to also help clean up the interface
between the apex and the rest of the system.

Bug: 142420609
Bug: 144864180
Bug: 145014493
Test: atest CtsBatterySavingTestCases:DeviceIdleTest
Test: atest CtsSecurityTestCases:DeviceIdleControllerTest
Test: atest FrameworksServicesTests:AppStandbyControllerTests
Change-Id: I1d248a075992e2dc279a7bfec44f38c7e51780b4