Unit Tests for Security Patch Level

Merge of widevine change http://go/wvgerrit/16249

This CL adds unit tests and reference code for the security patch
level, which is a new feature in OEMCrypto v11.  This CL also adjusts
the dynamic and static adapters to still run with devices that have a
v10 OEMCrypto.

The level 3 haystack code will be updated in a future CL.

bug: 26188985

Change-Id: I518ef46b4098cf3718fe0c0390bfb6825db4fb6b

libwvdrmengine/oemcrypto/mock/src/oemcrypto_engine_device_properties.cpp

@@ -50,4 +50,10 @@ const char* CryptoEngine::security_level() {
   return "L3";
 }
 
+// This should start at 0, and be incremented only when a security patch has
+// been applied to the device that fixes a security bug.
+uint8_t CryptoEngine::security_patch_level() {
+  return 0;
+}
+
 }  // namespace wvoec_mock