Add optional 'execution mode' to CIF simulator

We added a documented execution scheme to the CIF controller checker in #970 (closed). All code generators now adhere to it.

This issue concerns one of the follow-ups from #970 (closed), namely to add an optional 'execution mode' to CIF simulator. This allow to get the same behavior as implementations / generated code. This can help in validation. From #970 (comment 2818190):

Giving the simulator an execution mode, but not enabling it by default, means that users can reduce their validation effort, but they have to explicitly enable it, and thus should be aware of what they are doing. It can be very practical,

Addresses #679, #970 (closed)