"Data during calls" toggle not working.

1) Have DataEnabledSettings listen to Call state change,
so that mIsDataEnabled is updated in time.

2) In DataEnabledOverride, when evaluating CONDITION_IN_VOICE_CALL,
also check if IMS call is active.

Bug: 134981077
Test: manual and unittest
Change-Id: Ia97b6c5b9bb3a0a1a546dde7dee1192feefe00b6