Mark dummy classes as final

```
RadarDummy
GameWindowDummy
MouseDummy
ParticleSystemManagerDummy
ViewDummy
MilesAudioManagerDummy
GameWindowManagerDummy
GhostObjectManagerDummy

W3DScorchDummy (soon to be added in an upcoming PR)
```

(list may be incomplete)

Seems to me that these dummy classes can be marked as `final` to increase the potential for de-virtualization optimizations.