Implement model commands

- [ ] Fetch list (defaults to all)
- [ ] Fetch list by filter
- [ ] Fetch item (param 1 defaults to ID)
- [ ] Fetch item by filter

```
./bin/arken game.getEras 
./bin/arken game.getEras `{ where: { status: { equals: "Active" } } }`
./bin/arken game.getEra 66d242abcfa9286652ddea64
./bin/arken game.getEra `{ where: { name: { equals: "Prehistory" } } }`
```