Support CarrierConfigChangeListener in CarrierConfigLoader

Bug: 244087782
Test: atest CarrierConfigLoaderTest

Merged-In: Ic383135b3cc09f282f99b21839703d6b80032f3c
Change-Id: Ic383135b3cc09f282f99b21839703d6b80032f3c
(cherry picked from commit d63ba34af214f54242bc5fd08b7d09fb63c1fa68)
2 files changed