Having an unified method for separated broadcasting

Both DistractingPackageHelper and SuspendPackageHelper broadcast with
package names/uids separately. Having an unified method to calculate
the list to reduce code duplication.

Bug: 227270414
Test: atest AppEnumerationTests
Test: atest BroadcastHelperTest
Test: atest CtsSuspendAppsTestCases
Test: atest DistractingPackageHelperTest
Test: atest SuspendPackageHelperTest
Change-Id: Ie900be9e8f8a306f06e9856a25965c7a9e08b684