Galactic news events when certain things are researched/built/etc

**What do you want to see?**
Like in certain Civ games where you would be told when an empire has completed the Manhattan Project. Here we might flag things such as researching stellar manipulation or building a sphereworld.

**How would it help players?**
Give players more info on the galaxy around them.

**Alternatives**
N/A

**Screenshots and mockups**
N/A

**Things to consider**
What of empires you haven't encountered? I see three options:

* No message for these events
* Message for these events but the empire name is redacted, it just says "An Unknown Empire" (as in Civ)
* Message for these events with the full empire name

This affects mods because the mod files would specify which techs, components, etc. would trigger the messages when researched/built.