[SB refactor] Add connectivity tracking to the mobile pipeline

This CL tracks 2 bits from ConnectivityManager for mobile networks:
isConnected and isValidated. These bits are used to know whether or not
cellular networks are the default transport, and whether or not
connectivitymanager has validated that transport.

Test: manual
Test: atest packages/SystemUI/tests/src/com/android/systemui/statusbar/pipeline/mobile/*
Bug: 240492102
Change-Id: I13890cdc59c198c1b5290ae92e7ec4ba491999e3