creationSourceAbility error on StarBasePsi

[eljeffeg]

We have starbase with a missing creationSourceAbility, StarBasePsi.entity. While StarBasePsi is referenced by several things in the mod, I'm don't see that we have an Ability to create it. So I'm not sure what to put in creationSourceAbility or if the Starbase even gets created. It's in the GalaxyScenarioDef.galaxyScenarioDef, so it's possible it could get spawned upon game startup or an event. If we can remove the Starbase from the mod, that might work best, otherwise, we should put something acceptable in the field.