vms/platformvm: Move GetRewardUTXOs, GetSubnets, and GetChains to State interface
#2123
| Job | Run time |
|---|---|
| 6m 54s | |
| 4m 32s | |
| 21m 46s | |
| 10m 35s | |
| 1m 18s | |
| 1m 29s | |
| 46m 34s |