Add Device info validator to oemcrypto util and unit tests

Validator that can parse and validate device info Cbor object.
This is to support better prov40 unit tests regarding
OEMCrypto_GetDeviceInformation() later.

Test: opk_ta_p40
Bug: 300304834
Change-Id: Ic260a6626dffcbef5d6b386263839499f83a69db

libwvdrmengine/oemcrypto/util/include/cbor_validator.h

@@ -68,6 +68,12 @@ class CborValidator {
   // Writes validation output |msg| to |validate_messages_|, and updates
   // |message_status_| if the |status| is more severe than the current value.
   void AddValidationMessage(CborMessageStatus status, const std::string& msg);
+  static const cppbor::Item* GetMapEntry(const cppbor::Map& map,
+                                         const std::string& entry_name);
+  // Checks whether an entry with |entry_name| and |major_type| exists in |map|.
+  static std::string CheckMapEntry(const cppbor::Map& map,
+                                   cppbor::MajorType major_type,
+                                   const std::string& entry_name);
   CborMessageStatus message_status_ = kCborUninitialized;
 
  private: