Add auto data switch feature

The feature is enabled via
TelephonyManager.MOBILE_DATA_POLICY_AUTO_DATA_SWITCH. The feature only
applies to non-DDS. If enabled, we automatically switch to the non-DDS for data traffic when it has better availability than the DDS.

Bug: 244064524
Test: cts + UT + manual test in DSDS/single sim/wifi/APM scenario.
Change-Id: I0aa793d73f88de022944566d34f889b894f3b24f