Extending BookingArrangement and fixing it

[ue71603]

• Fixing the duplication in ServiceBookingArrangement.
• Extension for some standard limitations (age, limitation in parallel to existing public transport according to the Basecamp discussion: https://3.basecamp.com/3256016/buckets/2570434/messages/8778284879

On Nicks entries I suggest to go with

• ELIGIBILITY: If we added a new specialisation of BOOKING ARRANGEMENTs (e.g. BOOKING ELIGIBILITY RESTRICTION
• COMPETITIVE RESTRICTIONS: I would prefer to use i here, as then we don't have to wait for CoRoM, which is not in the current scope of either 1.3 or 2.0. We can revisit it later. We model it as an extension to booking arrangement and we need to allow for booking arrangement on ServiceJourney, Connection and ServiceeJourneyInterchange besides Line.

[ue71603]

@skinkie Ok for you to do this in 1.3 (aka main)