Suppress error for removing lingering offline licenses.

[ Merge of http://go/wvgerrit/97963 ]

There are situations where an offline license file will remain on the
system after it's usage entry has been deleted.  This would result in
its key set ID being reported as present by the CDM, but any
operations acting upon it will result in an error.

The app should be able to remove the license without error, so long
as the license file exists and no other OEMCrypto operations fail.

This change introduces a new error code LICENSE_USAGE_ENTRY_MISSING,
which indicates that a license's usage entry cannot be found.

A new integration test checks that the CDM can handle the calls to
removeOfflineLicense().

Bug: 137034719
Test: Android unit and integration tests
Change-Id: Ibdbe963b7f7e3ac97b446300d8e3896cdee7abc5

libwvdrmengine/include/WVErrors.h

@@ -292,10 +292,11 @@ enum {
   kLoadUsageEntryInvalidSession = ERROR_DRM_VENDOR_MIN + 309,
   kMoveUsageEntryDestinationInUse = ERROR_DRM_VENDOR_MIN + 310,
   kShrinkUsageTableHeaderEntryInUse = ERROR_DRM_VENDOR_MIN + 311,
+  kLicenseUsageEntryMissing = ERROR_DRM_VENDOR_MIN + 312,
 
   // This should always follow the last error code.
   // The offset value should be updated each time a new error code is added.
-  kErrorWVDrmMaxErrorUsed = ERROR_DRM_VENDOR_MIN + 311,
+  kErrorWVDrmMaxErrorUsed = ERROR_DRM_VENDOR_MIN + 312,
 
   // Used by crypto test mode
   kErrorTestMode = ERROR_DRM_VENDOR_MAX,