Integration Tests

• Using a stage that disallows views inside of $_documentResultsAndMetadata correctly throws an error.
• $_documentResultsAndMetadata fails when both in a view and on a view (first stage constraint).
• $_documentResultsAndMetadata correctly propagates a nested view to its source stage.
• $_documentResultsAndMetadata correctly propagates a view to its sub-pipelines when a view application is nested deeply in its source stage (e.g. $_documentResultsAndMetadata.{$unionWith | $lookup | $_documentResultsAndMetadata}).