Simple design for empty node (#15087)

I did an acceptable design for empty node and iterators for release:
- use array field for iterator node. Added an util to stringify arrays
for backward compatibily
- remove icon for empty node
- allow to select a node on empty node selection


https://github.com/user-attachments/assets/b00037a8-aa1d-4784-b973-05973649b46e

packages/twenty-front/src/modules/workflow/workflow-steps/components/WorkflowRunStepNodeDetail.tsx

@@ -250,7 +250,6 @@ export const WorkflowRunStepNodeDetail = ({
           return (
             <WorkflowEditActionEmpty
               key={stepId}
-              action={stepDefinition.definition}
               actionOptions={{
                 readonly: true,
               }}

packages/twenty-front/src/modules/workflow/workflow-steps/components/WorkflowStepDetail.tsx

@@ -224,13 +224,7 @@ export const WorkflowStepDetail = ({
           );
         }
         case 'EMPTY': {
-          return (
-            <WorkflowEditActionEmpty
-              key={stepId}
-              action={stepDefinition.definition}
-              actionOptions={props}
-            />
-          );
+          return <WorkflowEditActionEmpty key={stepId} actionOptions={props} />;
         }
         default:
           return assertUnreachable(