Example of efficiently writing an IEnumerable to a FileResult.
The EnumerableFileResult<T> class can be initialized
with an IEnumerable<T> and when executed by the
ASP.NET Core pipeline in enumerates through the
enumerable and using a custom adapter, IStreamWritingAdapter<T>,
writes each item to the response stream (HttpContext.Response.Body).
More details and reasoning at: http://philipm.at/2018/enumerablefilestreamer.html