Expose status, add backward compat in tests and remove unused code

* Expose release and offline statuses in CdmEngine.

  [ Merge of http://go/wvgerrit/14616 ]

  This will allow me to make some intelligent decisions in the new CE
  CDM implementation without having to duplicate all the information
  known in the lower levels.

* Account for backward compat support in tests

  [ Merge of http://go/wvgerrit/14621 ]

  One test ensures that device path backward compatibility is working,
  while another assumes it is used.

  This fixes test results when
  Properties::security_level_path_backward_compatibility_support()
  is false.

  Previously, the CE CDM did not run these tests, and so this went
  unnoticed.

* Remove Lock::Try, which is not used.

  [ Merge of http://go/wvgerrit/14624 ]

Change-Id: Id18cf1f5b18c7322b8b636819276361af225734f

libwvdrmengine/cdm/core/include/lock.h

@@ -21,10 +21,6 @@ class Lock {
   void Acquire();
   void Release();
 
-  // Acquires a lock if not held and returns true.
-  // Returns false if the lock is held by another thread.
-  bool Try();
-
   friend class AutoLock;
 
  private: