[C#] Add support for `IEnumerable<T>` for Views' return types

[rekhoff]

Introduced in #4393 during the change from Query<TRow> to IQuery<TRow>, Views can no longer return IEnumerable<T> as a return type. Now users must return a List<T>, and take any existing IEnumerable<T> and use .ToList() to return the supported type.

This resulted in the documentation change seen in #4392 on 00500-cheat-sheet.md

Goal:

Add support for IEnumerable<T> as a valid return type for Views, eliminating the need for using the return type of List<T> and use of .ToList() on Query Builder results.