Show a dynamic menu when examining vehicle parts.

This solves https://github.com/CleverRaven/Cataclysm-DDA/issues/5689

This shows a dynamic menu when examining vehicle parts.

The first entry is always "Examine vehicle"
Then if the part has items stored, "Get items"
Then if the part has a kitchen unit, "Use hotplate", "Fill a container with water", "Have a drink"
Then if the part has a craftrig, "Use water purifier?"
Then if the part has a chemlab, "Use the chemistry lab's hotplate?"
Then if the part has a welding rig "Use the welding rig?"