cbor_value_byte_string_equals ?

Hi,

There is a function in `cborparser.c`: `cbor_value_text_string_equals` which checks if a char array is equal to the cbor value string. It would be helpful to also have this for a byte string, ie:

```
CborError cbor_value_byte_string_equals(const CborValue *value, const char *string, size_t len, bool *result)
{
CborValue copy = *value;
CborError err = cbor_value_skip_tag(©);
if (err)
return err;
if (!cbor_value_is_byte_string(©)) {
*result = false;
return CborNoError;
}

return iterate_string_chunks(©, CONST_CAST(char *, string), &len, result, NULL, iterate_memcmp);
}
```

This can't easily be implemented outside of the `cborparser.c` file because `iterate_string_chunks` is a static method contained to just this file.

I am happy to create a PR with this if that would help (I'm also happy to have someone else add it too), but I just wanted to check if this would be accepted?

Thanks.