[ 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
de779e7545