Add built-in, commonly used query types to the Integration API.

Candidates, by order of importance:

• eZ:Children: Children of a location, immediate or as a tree (relative depth handling)
• eZ:RelatedToContent: Reverse relations
• eZ:Siblings: "sister" items of a location
• eZ:Ancestors: ancestors of a content or location
• eZ:GeoLocation: By geographic proximity (map location)

Requirements:

• all must accept objects as parameters, and may also support scalars as an alternative (content id instead of content)
• all must support filtering by content type
• all must support paging with consistent naming
• all must support sorting
• all must validate parameters (using OptionsBasedResolver or something else)
• all must ignore invisible items by default, with an option to display them
• all should be limited to the active siteaccess tree root
• when applicable, both content and location should be supported (pass the location to use the content, pass the content to use the main location...)

Extras to consider:

• they should be easy to extend or re-use, for instance to add custom field based filtering