Cache getPhoneId and getSlotIndex binder calls.

Use PropertyInvalidatedCache to avoid redundant calls to
SubscriptionController getSlotIndex and getPhoneId.
Bug: 151953109
Test: Verified cache operated correctly when phone process is killed.
Test: atest SubscriptionControllerTest
Test: atest android.telephony.cts.SubscriptionManagerTest

Change-Id: I70552537af44f3e05b156cd190ebb28f0d940bf6