Add support for KEY_TYPE_RELEASE for clearkey plugin.

Test: android.media.cts.MediaDrmClearkeyTest#testReleaseOfflineLicense
Test: android.media.cts.MediaDrmClearkeyTest

bug: 117617857
Change-Id: I74b7db2824ca91f1301bba6404e4e900dde290d2
8 files changed