Add GetVersion API to query the client plugin version.

Includes Widevine libraries 4.5.0.8097

Change-Id: I7590d5a60f300f6686887f62ae127b86f76e6f94
related-to-bug: 6000505

proprietary/drmwvmplugin/include/WVDRMPluginAPI.h

@@ -72,6 +72,7 @@ class WVDRMPluginAPI {
     virtual bool RemoveAllRights() = 0;
     virtual bool Prepare(char *data, int len) = 0;
     virtual int Operate(char *in, int inLength, char *out, int outLength, char *iv) = 0;
+    virtual std::string GetVersion() const = 0;
 
     enum EventType {
         EventType_AcquireDrmInfoFailed,