Some success payload need to have Messages

[jessymallet]

When some tools are used, some message should be displayed to the user from the frontend.
For example, when a user try to Drag and drop an element in an other one, the user should be informed that the DnD is not possible or user could be informed of additional information.

To inform user, we would like to use org.eclipse.sirius.components.representations.Message. Unfortunately the DropOnDiagramSuccessPayload cannot encapsulate Message. Only failurePayload could display Message.
But org.eclipse.sirius.components.collaborative.diagrams.handlers.DropOnDiagramEventHandler return failure only if org.eclipse.sirius.components.view.emf.diagram.DiagramOperationInterpreter.executeTool(Tool, VariableManager) return a failure. The DnD AQL expression is evaluated with no error so there is no failure.

It would be interesting that DropOnDiagramSuccessPayload can encapsulate Message to display to the user. For example, on EditTextField request, we can see that the successPayLoad can encapsulate Message (see screenShot).

Several successPayload could be completed with Message :

• DropOnDiagramSuccessPayload
• DeleteFromDiagramSuccessPayload
• SucessPayload from ReconnectEdgeEventHandler
• EditLabelSuccessPayload

• I have checked that this bug has not yet been reported by someone else
• I have checked that this bug appears on Chrome
• I have specified the version : 2023.10.1
• I have specified my environment : Windows 11

Screenshots

Steps to reproduce

• try to add Message on Drag and Drop service

Expected behavior

• Message is displayed to inform user

Actual behavior

• No Message is displayed to inform user.