Bug/618 operator scope

### Description
Scope operators no longer accepted in the payload.
The 'Not' operator is now merged into the scope type.

Don't use "Not" literally, but the define. I mean:

```
#define SCOPE_FILTER_NOT_EXISTENCE SCOPE_FILTER "::" SCOPE_OPERATOR_NOT "::Existence"
```

(Not sure right now about the right syntax to concatenate string in #define, but I think you get the idea)