[DEV][TASK 10505] Compute billed quantity
[FIX] Missing translation module
[IMP][TASK 10505] Improve billed quantity computation
[DEV][TASK 10505] Add billed quantity in invoice view
[IMP][TASK 10505] Refactor
[FIX] Still use pricelist version if no start and/or end date
[MERGE][TASK 10505] TOS: Only show the billed quantity on invoice if free period