QTiffHandler::supportsOption(QImageIOHandler::Description) returns false even though the TIFF format supports comments

Even though the underlying TIFF format (as well as libtiff) support comments in the generated file (via TIFFTAG_IMAGEDESCRIPTION), the implementation of QTiffHandler::supportsOption() returns false for Description, resulting in any metadata added to the QImage via QImage::setText() to be lost when saving a QImage as TIFF.

To be consistent with other image formats properly supporting saving the metadata as long as the format supports it, TIFF images should save that data as well.