Canonicalize data on snapshot restore

[lgfa29]

When Nomad restore state it may replay individual Raft logs into memdb or restore a full snapshot. These code paths are different, with the first one being usually handled by a method StateStore.Upsert*() and the second with StateRestore.*Restore().

To make sure state is consistent we should ensure data canonicalized on both paths (and that doing so doesn't break anything).