[ Merge of http://go/wvgerrit/115550 ]
This change is the first part of a three part change for restructing
the root of trust used by the reference implementation.
The API of the AuthenticationRoot class has been updated to reflect
the OEMCrypto functions that relate to the root of trust. This
involves changing the keybox and DRM Cert methods and adding in new
stubs for OEM Certificates.
The WvKeybox now uses a RAII-like interface to ensure that keyboxes
are provisioned correctly or not at all.
Bug: 135283522
Test: oemcrypto_unittests ce_cdm_tests
Change-Id: I3f2baf29c1022e1806b6196fa6650d761785c626