Workflow - Stop a run from the UI

[thomtrp]

Desired Behavior

If workflows are stuck into a running mode because of code step too long or a bug, or because of pending forms, there are no quick ways to cancel the execution. The run could also be started by mistake.

We should provide the user with a "Cancel Run" action from UI.

[thomtrp]

@Bonapara wdyt?

[Bonapara]

We can add a stop button on the workflow run showpage