make UiccSlotMapping constructor a system API

UiccSlotMapping need to be constructed and passed from LPA app to telephony framework API setSimSlotMapping, thus need to be exposed.
the real API to setSimSlotMapping was already protected with the privileged permission.

Bug: 214306205
Test: atest UiccSlotMappingTest
CTS-Coverage-Bug: 214446121

Change-Id: I109575750ab16ee9b73a469633372e93f03d2199
2 files changed