Also added a unit test to verify that decryption without a license fails with the correct error code. Also changed comment types for policy integration tests and core integration tests to be picked up by Doxygen. Bug: 320785945 Merged from https://widevine-internal-review.googlesource.com/194910 Change-Id: Ibdb70683003bb430dde9b4a1bd9fc9839bace342