Remove error OEMCrypto_KEY_NOT_LOADED

Merge from master branch of Widevine repo of http://go/wvgerrit/66066
Merge from oemcrypto-v15 branch of Widevine repo of http://go/wvgerrit/63628

The error code OEMCrypto_KEY_NOT_LOADED is redundant with
OEMCrypto_ERROR_NO_CONTENT_KEY and OEMCrypto_KEY_NOT_ENTITLED.  The
function LoadEntitledContentKey should return KEY_NOT_ENTITLED if it
does not find the corresponding entitlement key in its key table.  All
other functions that do not find a key id in the key table should
return OEMCrypto_ERROR_NO_CONTENT_KEY.  This includes QueryKeyControl,
SelectKey, and RefreshKeys.

Test: unit tests
Test: tested as part of http://go/ag/5501993
Bug: 115574797
Change-Id: Ida2111f32e331b99f3f0c77fa404a42654d0870c

libwvdrmengine/include_hidl/mapErrors-inl.h

@@ -30,6 +30,9 @@ static Status mapCdmResponseType(wvcdm::CdmResponseType res) {
     case wvcdm::KEY_NOT_FOUND_IN_SESSION:
     case wvcdm::NEED_KEY:
     case wvcdm::NO_MATCHING_ENTITLEMENT_KEY:
+    // TODO(http://b/119690361): there are several NO_CONTENT_* errors.
+    // that should probably all turn into NO_LICENSE.  Here, and below, and
+    // everywhere.
     case wvcdm::NO_CONTENT_KEY_3:
       return Status::ERROR_DRM_NO_LICENSE;