[CDM] Add CompanionExemptionProcessor

1. Auto revoke now checks if there's any association for the package.
2. Power saver now checks if there's any connected device for the
   package.
3. OnPackageModified no longer invalidates all the packages for the
   user.

Bug: 373957005
Test: manually tested 3 exemptions
Flag: EXEMPT bugfix

Change-Id: Icf1cc447306b7695767a713df78a763649e24f9d