Introduce DistractingPackageHelper

Move the implementaion of handling distracting packages out of the
PackageManagerService.

Fix: 225784320
Test: atest CtsSuspendAppsTestCases:DistractingPackageTest
Test: atest CtsSuspendAppsPermissionTestCases:NegativePermissionsTest
Test: atest CtsAppEnumerationTestCases:AppEnumerationTests
Test: atest FrameworksServicesTests:PackageManagerSettingsTests
Test: atest FrameworksServicesTests:PackageUserStateTest
Change-Id: I4e44c1f039318bf02d00ff6a6b8b973244108008