Moves `wp.media.model.Query` sorting and searching to the parent `wp.media.model.Attachments`.
Query parameters are stored in `attachments.props`, which is a `Backbone.Model`, and supports `order` (`'ASC'` or `'DESC'`), `orderby` (any `Attachment` model property name), `search` (a search term), and `query` (a boolean value that ties the `Attachments` collection to the server).
`wp.media.query( args )` now returns an `Attachments` set that is mapped to a `Query` collection instead of the `Query` collection itself. This allows you to change the query arguments by updating `attachments.props` instead of fetching the mirrored arguments, changing them, and passing them to `wp.media.query()` again.
fixes#21921, see #21390, #21809.
git-svn-id: http://core.svn.wordpress.org/trunk@21898 1a063a9b-81f0-0310-95a4-ce76da25c4cd