Add `Parallel` method

[WhiteBlackGoose]

Prototype

public static TOut[] Parallel<T, TOut>(this T @this, params Func<T, TOut> toRun)
    => Task.WaitAll(toRun.Select(Task.Run));

Comments

There also should be an Action-based overload.

Also, a method which would run async lambdas and async actions.

Unresolved questions

What's the name for the method?

How do we not confuse async lambdas with lambdas returning a task?