Fix #4122: Remember vehicle/seat when ped/player dies

[iManGaaX]

Summary

getPedOccupiedVehicle and getPedOccupiedVehicleSeat now work on dead players/peds server-side (like the client-side)

Motivation

Dying inside a vehicle clears the occupant link server-side, but the client keeps the ped paired with the vehicle until it respawns, so getPedOccupiedVehicle returned false server-side while returning the vehicle client-side

Closes #4122.

Test plan

Enter a vehicle, die inside it and call getPedOccupiedVehicle; should return the vehicle

Checklist

• Your code should follow the coding guidelines.
• Smaller pull requests are easier to review. If your pull request is beefy, your pull request should be reviewable commit-by-commit.