Remove Sub-Licenses and Sub-Sessions

(This is a merge of http://go/wvgerrit/66643)

The sub-license feature has been removed from the server and packager.
So that we do not have to continue maintaining the code that supports
this feature that never shipped, I am removing it from the CDM as well.

Bug: 113165466
Test: CE CDM Unit Tests
Test: Android Unit Tests
Change-Id: I5d25844b161e74aa19adf19a29c56e4881aa7304

libwvdrmengine/cdm/core/include/key_session.h

@@ -16,7 +16,7 @@ class KeySession {
   KeySession(metrics::CryptoMetrics* metrics) : metrics_(metrics) {}
 
  public:
-  typedef enum { kDefault, kSubLicense, kEntitlement } KeySessionType;
+  typedef enum { kDefault, kEntitlement } KeySessionType;
   virtual ~KeySession() {}
   virtual KeySessionType Type() = 0;
   virtual bool GenerateDerivedKeys(const std::string& message) = 0;
@@ -43,8 +43,6 @@ class KeySession {
   metrics::CryptoMetrics* metrics_;
 };
 
-typedef std::map<std::string, CryptoSessionId> SubLicenseSessionMap;
-
 }  // namespace wvcdm
 
 #endif  // WVCDM_CORE_KEY_SESSION_H_