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/initialization_data.h

@@ -31,9 +31,6 @@ class InitializationData {
   const CdmInitData& data() const { return data_; }
   std::vector<uint8_t> hls_iv() const { return hls_iv_; }
   CdmHlsMethod hls_method() const { return hls_method_; }
-  // TODO(jfore): Perhaps this should be a generic structure with the ids for
-  // any type of licensing?
-  std::vector<video_widevine::SubLicense> ExtractSublicenseKeys() const;
   std::vector<video_widevine::WidevinePsshData_EntitledKey> ExtractWrappedKeys()
       const;