Unable to set Custom Date for Index Id before Adding event handler

[niemyjski]

Added a test that shows off that monthly/daily indexes are failing due to unable to set custom date via event handler. Custom dates are set before the handler this preventing us from having custom logic before the document id is created.

    private async Task OnDocumentsAddingAsync(IReadOnlyCollection<T> documents, ICommandOptions options) {
        if (HasDates)
            documents.OfType<IHaveDates>().SetDates();
        else if (HasCreatedDate)
            documents.OfType<IHaveCreatedDate>().SetCreatedDates();

        documents.EnsureIds(ElasticIndex.CreateDocumentId);

        if (DocumentsAdding != null && DocumentsAdding.HasHandlers)
            await DocumentsAdding.InvokeAsync(this, new DocumentsEventArgs<T>(documents, this, options)).AnyContext();

        await OnDocumentsChangingAsync(ChangeType.Added, documents, options).AnyContext();
    }