Avoid creating by hand vm binary in plugin-dir/vmid

it should be much easier to just specify binary name and let ANR copy the files into proper location
eg
```
go run main.go control start  --avalanchego-path ~/avalanchego-v1.11.10/avalanchego --blockchain-specs '[{"vm_name":"chain1","genesis":"~/genesis.json","vm_binary": "~/subnet-evm-v0.6.8/subnet-evm"}]'
```
this needs adding vm_binary to blockchain specs in rpc.proto 