[Request] More space stage functions

[VanillaCold]

• [ ] The ability to give the player a mission.
• [ ] A way of finding a planet through the Sporepedia in the Space Stage.
• [x] Some kind of method of switching the empire which owns a system, like the Fanatical Frenzy tool.
• [ ] A function to load inventory items such as creatures and spice, to add them to the player's space inventory. (like when collecting space items)
• [ ] a function to spawn tool projectiles