Enable the dbstat virtual table for sqlite

The dbstat table allows tools like sqlite3_analyzer to run and dump
statistics about the database. It also allows runtime queries for
information such as database size, which is needed for keystore2
metrics.

Bug: 172013262
Test: atest system/security/keystore2
Change-Id: Icbc58570f86ce9f4d275a0bed7cc356e3369435d