Added debugOtaKeyboxFallbackDuration property.

[ Cherry-pick of http://ag/16064434 ]
[ Merge of http://go/wvgerrit/136330 ]

This changes adds a custom debug property for changing the fallback
policy used for the system.  Depending on the value set, the device
will either use a "fast" fallback (30 seconds) or "default" fallback
(~1 day with exponential backoff).  Setting this property to either
"fast" or "default" will end the current fallback if it has been
triggered.

Bug: 187646550
Test: Android unit tests
Change-Id: I5271f96139c1e468242f7fa742668cc791ffcf91

libwvdrmengine/cdm/include/wv_content_decryption_module.h

@@ -188,6 +188,9 @@ class WvContentDecryptionModule : public android::RefBase, public TimerHandler {
   virtual CdmResponseType GetSessionUserId(const CdmSessionId& session_id,
                                            uint32_t* user_id);
 
+  virtual bool SetDefaultOtaKeyboxFallbackDurationRules();
+  virtual bool SetFastOtaKeyboxFallbackDurationRules();
+
  private:
   struct CdmInfo {
     CdmInfo();