Use existing 'coordinatesForCell' method in more places
requested to merge michaelweghorn/orca:michaelweghorn/use_existing_coordinatesforcell_method into master
Make use of the existing 'coordinatesForCell' method in more places. This way, retrieving the row and column index there also happens by using the AT-SPI TableCell interface if the object implements it, which also avoids issues with child indices that don't fit into 32-bit (like for some cells in LibreOffice Calc).