Add TrueSettle

[lekcyjna123]

In #547 there is a point: https://github.com/kuznia-rdzeni/coreblocks/blob/757fcd527a5257a25c6202111fd3e237974a9aa1/test/common/profiler.py#L37

I have decided to implement a draft of such operator, but I have some doubts about the semantic. Should we allow changes in testbench signal inputs after issuing TrueSettle? From one side I can imaginate that we can want to do after all process are in steady state, but this can cause the next round of changes in signal values. So now I think that after TrueSettle no changes in input signals should be allowed.