Throw exception if an additional field was placed inside the "query" body

Currently the parser accepts queries like

```
"query" : {
     "any_query": {
         ...
     },
     "any_field_name":...
}
```

The "any_field_name" is silently ignored. However, this also causes the parser
not to move to the next closing bracket which in turn can lead to additional query
paremters being ignored such as "fields", "highlight",...
This was the case in issue #4895

closes issue #4895