Reading JSON documents unnecessarily creates a buffered copy of the document

[darrelmiller]

Suggestion to update to something like the following code in OpenApiModelFactory

        public static async Task<ReadResult> LoadAsync(Stream input, string format, OpenApiReaderSettings settings = null, CancellationToken cancellationToken = default)
        {
            Utils.CheckArgumentNull(format, nameof(format));
            settings ??= new OpenApiReaderSettings();

            Stream preparedStream;
            if (input is MemoryStream || format == "json")  // Added test for json format
            {
                preparedStream = input;
            }
            else
            {
                // Buffer stream so that OpenApiTextReaderReader can process it synchronously
                // YamlDocument doesn't support async reading.
                preparedStream = new MemoryStream();
                await input.CopyToAsync(preparedStream, 81920, cancellationToken);
                preparedStream.Position = 0;
            }

            // Allow StreamReader to read directly from FileStream or NetworkStream
            using var reader = new StreamReader(preparedStream, default, true, -1, settings.LeaveStreamOpen);  
            return await LoadAsync(reader, format, settings, cancellationToken);
        }