Support ARIA table attributes, skip layout tables, and don't get stuck on hidden cells (#7410)
* Add support for ARIA rowindex, colindex, rowcount and colcount in Gecko / Chrome for both browse mode and focus mode.
Specifically:
* IAccessible NVDAObject properties: rowNumber, columnNumber, rowCount and columnCount now expose the ARIA values if available, otherwise falling back to the original physical table information.
* Gecko controlField attributes: table-rownumber, table-columnnumber, table-rowcount and table-columncount now expose the ARIA values if available, otherwise falling back to the original physical table information
* New Gecko controlField attributes: table-physicalrownumber, table-physicalcolumnnumber, table-physicalrowcount and table-physicalcolumncount values always expose the physical table information no matter what the presentational values may be.
* Added new class variables to BrowseModeDocumentTreeInterceptor: navigationalTableRowNumberAttributeName and navigationalTableColumnNumberAttributeName which are used by BrowseModeDocumentTreeInterceptor._getTableCellCoords in place of the literal strings "table-rownumber" and "table-columnnumber" respectively, to allow fetching of the correct attributes containing physical table information.
* Gecko_ia2 VirtualBuffer: override navigationalTableRowNumberAttributeName and navigationalTableColumnNumberAttributeName To provide the use of table-physicalrownumber and table-physicalcolumnnumber.
* No longer include layout tables in table navigation commands
* Gecko browseMode: skip over hidden table cells in table navigation commands. MSHTML already did this.