Custom asteroid type name method
For real this time...
Use getAsteroidData instead of duplicating code
Corrections to `getAsteroidData()`.

`AsteroidDataRepository.getAsteroidData()` now works for initialized but unloaded vessels.

Moved `getAsteroidTypeName()` from `AsteroidDataRepository` to `CustomAsteroidData`. Added analogous access methods for other CAD fields.