This property affects safe compat because the ID is what gets preserved
in the save, but it's unfortunately also used as the display name, which
means changing the display name breaks save compat. It also prevents us
from changing display names without breaking faction definitions.
This is the first step in fixing that. The next is adding a separate
display_name property that can be updated without breaking either of
those.
This is needed fairly often, and we have a lot of Game being passed
around to ControlPoint methods specifically to support this. Just store
the owning Coalition directly in the ControlPoint to clean up. I haven't
cleaned up *every* API here, but did that aircraft allocations as an
example.
