names: Revise random star cache data to distinguish materialized stars

Now we won't double count volatile and materialized stars in enumeration.
For example, star name labels had been displayed twice for a
materialized star, but it's no longer the case.
names: Add orbit to materialized stars to prevent precision loss

Previously, we have not provided a dedicated OrbitCS for warp
destination near randomly generated star.  It makes the destination
so far away from local CoordSys origin, which in turn make the
graphics jitter due to low floating point precision.
Also, we can make the arrived ships orbit around the star, which is
physically convincing behavior.