[DMN Designer] Switch grid toolbar button

The stunner based designers contain "Switch grid" button. The problem of this button for DMN Designer appears if the expression editor is opened. User has still possibility to use this button. It would be more logical to disable this button while expression editor is opened as the grid is not shown at that moment.

Manual acceptance test

Navigate between diagram and expression editor using [1] and check button enabled in diagram, disabled in expression
[1]

• Navigation dock
• Manually clicking elements