SAR missions check unoccupied cabin number, but should check overall number

[bszlrd]

Observed behaviour

I was unable to take two SAR missions simultenaously:

• One was close, and required the transfer of one pilot.
• The other required bringing back three people from a wreck.
  I took the first one, and wanted to take the second one, figuring that I will drop off the pilot, then head for the other ship.
  But I was refused from the second, because I did not have three unoccupied cabins due to having that pilot on board. (And the ship has a limit of three cabins)

Expected behaviour

I think I should have been able to take both missions. The mission should note refuse if there are unoccupied cabins, since it can't know if those cabins will still be occupied when the player gets to the target. Instead I think it could still give the mission, if there are enough cabins on the ship, no matter their occupancy, and notify that there might be not enough room.
From another POV: the game shouldn't hold the hands of the player. Let them fail missions if they aren't paying attention. (Of course for that it would be nice to be able to cancel missions)

Steps to reproduce

My pioneer version (and OS):
2024 0710

My output.txt (required) and game save (optional, but recommended)

[Web-eWorks]

Passenger logic is getting addressed in #5734 - this should be evaluated after that PR is merged.

[Web-eWorks]

Still valid after equip-v2 merge. This is a good low-hanging fruit for a first-time contributor though!