Improve 'set-cookie' — add an empty object value

Sometimes `{}` helps to prevent cookie or other popups.

Recent case - https://github.com/AdguardTeam/AdguardFilters/issues/203872
We used a trusted rule here, but `#%#//scriptlet('trusted-set-cookie', 'cksd', '{}')` also helps, without the value, set by script 

```
%7B%22choice%22%3A%22reject-all%22%2C%22features%22%3A%7B%22cf%22%3Afalse%2C%22pp%22%3Afalse%2C%22ca%22%3Afalse%7D%7D
```