Add discovered / undiscovered status to star systems in star map

[BarthPaleologue]

With the new discovery system introduced by #237, players can now discover orbital objects and said discoveries are recorded in the Encyclopaedia Galactica.

What would be nice is to update StarMapUI::shortHandUI to add an additional field displaying "Discovered by Player on Date" or "Undiscovered" depending on the discovery system of the status.

To get this status information, querying the Encyclopaedia Galactica for the star of the system will be necessary.

To that end, add EncyclopaediaGalactica::getDiscoveryInformation(object: OrbitalObjectId): SpaceDiscovery | null and implement it where needed as told by the compiler.