[ Merge of http://go/wvgerrit/118563 ]
Sync with the latest version of drm_certificate.proto to add in
certificate expiry time. Add in signed_drm_certificate.proto and remove
messages from device_certificate.proto.
SignedDrmDeviceCertificate and DrmDeviceCertificate are now named
SignedDrmCertificate and DrmCertificate. This necessitated non-proto
changes.
Bug: 169740403
Test: WV unit/integration tests
Change-Id: Ie5969ac7217a25eb075a41df59b77da2becd4545
0cf99f685f