Specify how "and" and "or" work with VPR

[dlongley]

Top-level queries are "and", so e.g.:

{
  query: [
    // "and"
    {
      type: 'APopularQueryType',
      // query details ...
    },
    // "and"
    {
      type: 'AnotherQueryType',
      // query details ...
    }
  ]
}

And "or" queries are possible within particular query types like this:

{
  "query": [
    // "and"
    {
      "type": "QueryByExample",
      "credentialQuery": [
        // "or"
        { ... },
        // "or"
        { ... }
      ]
    },
    // "and"
    { ... }
  ]
}