Keystore 2.0: Move per-boot database out of SQLite

Being in SQLite incurs a variety of overheads. Originally, the per-boot
database was in SQLite with the intention of living in a temporary file
to allow keystore2 to restart without losing auth token state. Since
keystore2 is not allowed to crash, it was moved to an in-memory SQLite
database. Since it is no longer vfs backed, we do not need to pay the
memory, speed, and complexity costs of SQLite for it any longer.

Bug: 186436093
Test: atest keystore2_test
Test: atest CtsKeystoreTestCases
Change-Id: I5c219d294af1876a18a7fdef40307f3b92ae4b8b
8 files changed