Check access to user and password fields in APN db

When apps query the APN db and filter on the user or password fields,
make sure they have the proper permission for accessing APN data.

Bug: 124107808
Test: CTS
Merged-In: I96dc8d2b82571e31c958ae3d243c8d5daebea01c
Merged-In: Ia7be0ecdfca5e7adf6163dc015a413a98f1b9287
Change-Id: I96dc8d2b82571e31c958ae3d243c8d5daebea01c
(cherry picked from commit 9a74213831bac05c1bbc3183ab8e2f182e5e50cb)
2 files changed