…ko / 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, otherwising 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.

…mmands. MSHTML already did this.

* In the gecko vbufBackend: comment why two sets of table attributes are being added.
* browseModeDocumentTreeInterceptor._getNearestTableCell: make the retry limit configurable via a _missingTableCellSearchLimit property.
* browseModeDocumentTreeInterceptor._getNearestTableCell: try more cells for any LookupError not just hiddenTableCellFound (browsers such as chrome do not expose hidden cells).
* remove browseMode.HiddenTableCellFound
* Gecko_ia2 virtualBuffer's _getTableCellAt: raise LookupError if a hidden cell is found rather than HiddenTableCellFound