Previously, the same runner could be used multiple times with different submissions simultaneously. This, however, yielded errors, for example when one submission time oud (causing the running to be deleted) while another submission was still executed.
Admin actions, such as the shell, can be still executed regardless of any other code execution.
Fixes CODEOCEAN-HG
FixesopenHPI/poseidon#423
The errors are raised in the runner model and in the runner connection
class. In the submission controller the errors are rescued and,
depending on the error, the status timeout / container depleted is
sent to the client.
