Allow GSM RSSI levels to be customized by CarrierConfig

Add carrier config gsm_rssi_thresholds_int_array and mapping level
according to config

BUG: 123528673
Test: build pass and override carrierconfig to test

Merged-In: I61afd1f07564c0df886b0e30d27ea2a059b484dc
Change-Id: I61afd1f07564c0df886b0e30d27ea2a059b484dc
(cherry picked from commit b80dbce9)