feat: Allow custom query reviewer Any and None

Relates to #667 (closed)

Support for custom queries for reviewer Any or None

{
    //...
    "gitlab.customQueries": [
        //...
        {
            "name": "Items with reviewers",
            "type": "merge_requests",
            "state": "opened",
            "reviewer": "Any" | "None" //  <--- This is the significant change
        }
        //...
    ]
    //...
}