For new storage changes in Q, we need to redact the visibility of
the "_data" column on any returned cursors. We could cook this up
using SQLiteQueryBuilder projection re-mappings, but that's a pretty
involved change due to the number of tables and teasing apart
public-vs-hidden API columns.
Instead, this RedactingCursor class offers to "redact" requested
columns by replacing with specific values, such as "/dev/null".
Test: atest frameworks/base/core/tests/coretests/src/android/database/RedactingCursorTest.java
Bug: 111960973
Change-Id: Iad36986fc0b7a0cae10ff216755e284320991e18
a5d0bf1701