[Scenario Simulation] Update cell (double-)click interactions

Following from a discussion about https://issues.jboss.org/browse/DROOLS-2874 it was agreed that editing cells (header or body) in the grids should respond to single-click and not double-click.

Manual Acceptance Test

• Not possible edit multiple cells by hold CTRL and click on multiple cells
• Click column/row leading cell discard edit dialog
• Edit can be discarded by escape
• Edit can be discarded by click to canvas
• Invoke edit of cell
• Save and reopen
• Undo redo of editation