Task/570 type not exist

### Description
Two new URI parameters:
  - !exist='entity::type'
  - exist='entity::type'

The info can also be passed as a scope in requests that have restriction.
For this, a new field for the operation-scope in the input payload has been invented:
XML:

    <scope>
      <operationScope>
        <scopeOperator>not</scopeOperator>
      </operationScope>
    </scope>

JSON:
  "scopes": [
    {
      "operator": "not"
    }

Yeah, perhaps, but not necessarily.
One thing is the name of the URI option and another thing is the value of the scope. They don't HAVE TO coincide, however our lives are easier if they do ...

Now, "entity::type" is the name of an URI param so it needs to stay in this file to maintain a complete list of URI params.

If we also want to maintain a complete list of the Scopes, then there is no other choice than to use two different defines.  There is nothing wrong about it ...
I don't have a strong opinion about this (except for maintaining a complete list of the URI param names), so,  let's talk.