Field that indicates when a record is part of a trashed project
When "include_trashed" is true, records returned by the request should include an additional "in_trash" field which is true when the object is either directly trashed (is_trashed is true) or is part of a trashed project.
Note: it should be possible for "is_trashed" to be false and "in_trash" to be true. This means a collection isn't trashed directly, but that it is part of a project that is trashed. This is important because it has implications for how to "untrash" the specific object.
Note: "is_trashed" is an existing field name with existing semantics, which is why we need a new field. However the new field doesn't have to be called "in_trash", it could be something else if we can come up with a name that's less confusing.