Register PackageMonitor for CompanionDeviceManagerService

1. On package removed -> remove all its associations
2. On package updated -> if had associations, update special access permission
in accordance with (potentially changed) permission entries in manifest

Bug: 30932767
Test: 1. Remove app, and ensure xml entries for it got removed.
2. adb install new version of app without special permissions in manifest, and
ensure whitelist removal method got called
Change-Id: I87261c05ddcf40a18332d160b44ee2f8284df5e4