Add confirmation step for restarting a finished job

[m-mohr]

When restarting a finished job, old results usually get discarded. This is a single method execution without confirmation. We should ensure people don't do this by accident and ask for confirmation.

Origin: Open-EO/openeo-api#442

[danielFlemstrom]

I actually think the same goes for cancelled.

How about the following when receiving a start request on a finished or cancelled job:

1. A finished/cancelled job goes to created (which in practice means that you need to start it again, as confirmation)
   If you wish to add a confirmation pop-up, ask for the job status before.
2. Only remove old results when going from queued to running

[soxofaan]

I don't understand what you mean @danielFlemstrom

A finished/cancelled job goes to created

when? Automatically? or do you mean when restarting? But then you have to send the "start" request twice?

Only remove old results when going from queued to running

the "queued" state is an optional state (some back-ends might go from "created" to "running" immediately)

[danielFlemstrom]

I updated my previous comment about when to change status. However, thinking it over, it was an misunderstanding from my side. Ignore the comment for now.