CMTK0003 misses an array of Result tasks written in Task.WaitAll or Task.WaitAny #161

Found by the variant sweep of CMTK0003 before 2.3.0 (Variants/DroppedTaskShapes, the forms "Task.WaitAny of an array" and "Task.WaitAll of an array").

Problem

An array of tasks of results written inside a Task.WaitAll or Task.WaitAny call compiles with no CMTK0003, while the same tasks passed as separate arguments are reported at each call:

Task.WaitAll(orders.CancelAsync(first), orders.CancelAsync(second));            // CMTK0003 at each call
Task.WaitAll(new[] { orders.CancelAsync(first), orders.CancelAsync(second) });  // no diagnostic

The sweep measured it: the Result call missed 14 diagnostics, exactly the array forms' cases, while the assertion forms reported them.

Cause

new[] { … } is a Task<Result<…>>[], which converts to Task[] as a whole: no element is converted on its own, and AnalyzeConversion asks Producers of the array creation, which yields nothing.

Release

2.2.0 code can contain the form. It ships in 2.3.0 under decision 0119, in the PR for #152, #157 and #159.