Keystore 2.0: Make key type an explict argument.

This refactor makes key type an explicit to relevant database function
to make it harder to implicitly use the wrong type.

Ignore-AOSP-First: No automerge path from AOSP.
Bug: 187862706
Bug: 189470584
Test: Regression tested with keystore2_test.
Change-Id: I9e1416743093f0a1ab86fd9351aed97f106ee819
7 files changed