Implement mobile data preferred uids feature

- Read MOBILE_DATA_PREFERRED_UIDS setting when system ready
- Register MOBILE_DATA_PREFERRED_UIDS setting observer
- Send uid ranges to netd when update mobile data preferred uids

Bug: 171872461
Test: atest FrameworksNetTests
Merged-In: I5153c770650594e05dfa8cf230d7381d790f4a55
(cherry-pick with minor conflicts)

Change-Id: I5153c770650594e05dfa8cf230d7381d790f4a55
2 files changed