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/src/lock.cpp

@@ -27,10 +27,6 @@ void Lock::Release() {
   impl_->lock_.unlock();
 }
 
-bool Lock::Try() {
-  return (impl_->lock_.tryLock() == 0);
-}
-
 }  // namespace wvcdm