SettingsLib: wifi: add support for tracking carrier Wi-Fi APs

Added carrier network info AccessPoint to indicate if a given
AP is associated with a cellular carrier.

Bug: 30988281
Test: manual
Test: runtest --path
frameworks/base/packages/SettingsLib/tests/integ/src/com/android/settingslib/wifi/AccessPointTest.
java

Change-Id: I10e44b5e18099c7052a973ea24809e75bb2ba9ea