Revert "Revert "Allow overriding the label and icon of a MainCom..."

Revert submission 10921255-revert-10403399-pkg-override-label-icon-DCRMJNYAKW

Reason for revert: Re-submit broken change with included fix.
Reverted Changes:
Ic5c719cbb:Revert "Allow overriding the label and icon of a M...
Id9d37e661:Revert "Add test constructor to PackageManagerServ...

Bug: 113638339

Change-Id: I4f5247f528f62c175bd34f0e4cb16c9456c8afe4