Currently, it's possible to execute bhyvectl(8) with mutually exclusive
options, such as "--destroy" and "--suspend", and it will print out
obscure errors, e.g.:

bhyvectl --suspend=/var/run/vms/my_vm --destroy --vm my_vm
connect() failed: Connection refused

Address that by failing early if mutually exclusive options were
specified.

Additionally, move the BHYVE_SNAPSHOT block before the errors are
printed, so its errors are also displayed.