Add new MediaDrm methods

Methods for querying HDCP, security levels and
number of sessions

bug:64001680
bug:33657579

Test: cts: MediaDrmMockTest, ClearKeySystemTest
gts: GtsMediaTestCases

Change-Id: Ie616f96ab6b74410a3d7548a7f34b20cf0831d0c
3 files changed