Moved OEMCryptoResult string converter.

[ Merge of http://go/wvgerrit/170073 ]

Removed the file "error_string_util.cpp" and its header, moving the
OEMCryptoResult to string converter to "wv_cdm_types.cpp".  This extra
file served little purpose, and created a dependency on the CDM utils
to the CDM itself.

This is part of the effort to fix the formatting of WV metrics; making
enum-to-string conversion uniform throughout the CDM.

Bug: 239462891
Test: adb shell dumpsys android.hardware.drm.IDrmFactory/widevine -m
Test: Manual testing with Google TV
Change-Id: I4bf95d26b623f5b8fa86bdb2578cbc4ee65125cb

libwvdrmengine/cdm/core/test/test_printers.cpp

@@ -6,8 +6,6 @@
 
 #include "test_printers.h"
 
-#include "error_string_util.h"
-
 namespace wvcdm {
 void PrintTo(CdmResponseEnum value, ::std::ostream* os) {
   *os << CdmResponseEnumToString(value);
@@ -72,7 +70,7 @@ void PrintTo(const enum CdmCertificateType& value, ::std::ostream* os) {
 }
 
 void PrintTo(const enum OEMCryptoResult& value, ::std::ostream* os) {
-  *os << wvutil::OEMCryptoResultToString(value);
+  *os << OemCryptoResultToString(value);
 }
 
 namespace okp {