Debugger [CDB]: Enable Assignment to string classes.

Assign to QString/QByteArray following gdbmacros.py
implementation (call resize if required, copy data into buffer).

Assign to std::[w]string only it has sufficient memory
(since std::string<>.resize cannot be called).

src/libs/qtcreatorcdbext/stringutils.h

@@ -180,6 +180,9 @@ std::wstring stringToWString(const std::string &w);
 
 // String from hex "414A" -> "AJ".
 std::string stringFromHex(const char *begin, const char *end);
+// Decode hex to a memory area.
+void decodeHex(const char *begin, const char *end, unsigned char *target);
+
 std::wstring dataToHexW(const unsigned char *begin, const unsigned char *end);
 // Create readable hex: '0xAA 0xBB'..
 std::wstring dataToReadableHexW(const unsigned char *begin, const unsigned char *end);