Cache all certs and installed packages when initialized.

When CarrierPrivilegeTracker is initialized, it does not initially know
what the current CarrierConfig certs, SIM-loaded certs, or installed
packages are - each must be loaded before the Tracker can begin. These
values are fetched on the Handler thread to avoid blocking the Thread
used to instantiate the Tracker.

Bug: 147391402
Test: Tested on crosshatch build
Change-Id: I0605510af247ad591a37097b0ec2a6bcd5588556