Merge common code

Merge from Widevine repo of http://go/wvgerrit/57720

Now that we have oemcrypto mock split into reference and testbed code, it is
time to remove the part of testbed that is an exact copy of the reference code
and just use the reference code.

Test: unit tests
Bug: 76393338
Change-Id: I3831a3f0118221c21ff1c28e6b6101b27b889012

libwvdrmengine/oemcrypto/ref/src/oemcrypto_auth_ref.cpp

@@ -10,7 +10,6 @@
 
 #include "keys.h"
 #include "log.h"
-#include "oemcrypto_key_ref.h"
 #include "oemcrypto_rsa_key_shared.h"
 
 namespace {