Separate timer for availability and performance

Add res config: auto_data_switch_performance_stability_time_threshold_millis
as stability check when switch due to RAT/signal strength.

Use alarm manager to schedule timer longer than 1 minute.

Also, minor improvement on switching to default data if it has the same
score as the current, to honor user's preference.

Test: adb shell am broadcast -a com.android.internal.telephony.TestServiceState --ei phone_id 1 --ei data_rat 3
Test: inspect log to confirm
Test: internet browsing + voice call

Fix: 308456021
Change-Id: I061740bf0264ae622bc8774c3d52ae5331b21225