Implement Keystore 2.0 access control

This patch provides higher level functions to query Keystore 2.0
specific SEPolicy.
It provides abstractions for the permissions of the security classes
"keystore2" and "keystore2_key".
It also provides functions to check permission for general Keystore
requests as well as Keystore key and grant requests.

Bug: 159466840
Test: keystore2_test
Change-Id: Ie743cff76fe27f8ad96b2405f5d77b298ba35293
2 files changed