Gets a command to merge the selected cells.
readonly mergeTableCells: MergeTableCellsCommand
A MergeTableCellsCommand object that provides methods for executing the command and checking its state.
You can invoke this command by calling the execute method.
The execute method checks the command state (obtained using the getState method) before executing, and decides whether the action can be performed. The execute and getState methods are members of the MergeTableCellsCommand class.
The command merges table cells if the selection contains only a target range forming a rectangle without any unselected table cells.