Add possibility to decode v8 as v7 in the SciFi

Related to LHCb!4210 (merged), this is untested.

Data in June-July 2023 was interpreted as v7 banks, whereas the banks themselves were actually mislabelled v8. In order to reproduce this effect in MC, we introduce an option to force the decoding to version 7 even if the bank is version 8.

Solves LHCb#319 (closed)