I can rewind a process instance to a previous state

[SebastianStamm]

Is your feature request related to a problem? Please describe.

When testing a process, I need to complete process instance with different payloads to test different scenarios. To do so, I have to manually create the instances and click through them again and again, which is very time consuming.

Describe the solution you'd like
When completing a user task with a form, I want this form to be pre-filled with the values I entered previously so I just have to click the complete button for the form. In cases where there is no form, but I still completed the task with a variable payload previously, I want the previous payload to be reusable without having to enter it again.

In addition, I would like to "go back in time" and rewind a process instance to a previous state so I can quickly test different scenarios for a single task.

So, in summary:

• When opening the form of a user task, this form is pre-filled with the values of the previous completion of the same usertask
• User Task forms have a reset button in the footer of the modal that reverts any pre-filled values as well as any user input in the form
• Tasks without forms (e.g. service tasks or user tasks without forms) that were completed with variables before show a "Use previous response" button as primary action that completes the task using the same variable payload as before
  • The "Complete Job" action is still available via the dropdown
• Tasks that were completed show a "Rewind to this element" button
• Clicking this rewind button prevents the user from taking any other action until the rewind process is completed
• Clicking the rewind button creates a new process instance and uses saved history data to progress this new instance until the selected task becomes completable. The user is then redirected to this new instance.

Describe alternatives you've considered
#72 and #73 could be alternatives, but describe slightly different UX. They could still be valuable additions, even with the rewind functionality.