Async Linq CancelationToken parameters for async delegates

[timcassell]

Example, Where has

public static AsyncEnumerable<TSource> Where<TSource>(this AsyncEnumerable<TSource> source, Func<TSource, Promise<bool>> predicate);
public static AsyncEnumerable<TSource> Where<TSource, TCapture>(this AsyncEnumerable<TSource> source, TCapture captureValue, Func<TCapture, TSource, Promise<bool>> predicate);

But it's missing

public static AsyncEnumerable<TSource> Where<TSource>(this AsyncEnumerable<TSource> source, Func<TSource, CancelationToken, Promise<bool>> predicate);
public static AsyncEnumerable<TSource> Where<TSource, TCapture>(this AsyncEnumerable<TSource> source, TCapture captureValue, Func<TCapture, TSource, CancelationToken, Promise<bool>> predicate);

This is necessary to pass through the CancelationToken that is provided to AsyncEnumerable.GetAsyncEnumerator(CancelationToken) when the creator of the iterator has no control over how it's iterated (e.g. returning AsyncEnumerable<T> in a public API).