Add getNetworkSpecifier() and getCarrierConfig()

cherry-pick of https://android-review.googlesource.com/#/c/318111/

This allows making network request and getting carrier config on a
specfic SIM.

Bug: 32414216
Test: cts-tradefed run cts-dev --module CtsTelephonyTestCases
Change-Id: Iebe2d883e193afdde13303d76014dfd7f4fb06dd
Merged-In: Iebe2d883e193afdde13303d76014dfd7f4fb06dd

# Conflicts:
#	telephony/java/android/telephony/TelephonyManager.java