Display Data is not populated on Window.Configure

This is because a `Window.configure()` is implemented in terms of a Flatten and setting the output windowing strategy, rather than a primitive transform. The flatten cannot have associated display data. Display data is properly populated on the enclosing window transform, however.

Imported from Jira [BEAM-2064](https://issues.apache.org/jira/browse/BEAM-2064). Original Jira may contain additional context.
Reported by: tgroh.

Start with Window.configure() and inspect how it uses Flatten and the output windowing strategy. Compare this with the enclosing window transform's display-data behavior; done means Window.Configure exposes the expected display data rather than leaving it only on the enclosing transform.

Written by the indexing model from the issue text.