The NUMA topology struct field `NodeIDs` is a `idset.Set`, which has no public
members. As a result, this field is never serialized via msgpack and persisted
in state. When `numa.affinity = "prefer"`, the scheduler dereferences this nil
field and panics the scheduler worker.
Ideally we would fix this by adding a msgpack serialization extension, but
because the field already exists and is just always empty, this breaks RPC wire
compatibility across upgrades. Instead, create a new field that's populated at
the same time we populate the more useful `idset.Set`, and repopulate the set on
demand.
Fixes: https://hashicorp.atlassian.net/browse/NET-9924
Unsupported environments like containers or guests OSs inside LXD can
incorrectly number of available cores thus leading to numalib having trouble
detecting cores and panicking. This code adds tests for linux sysfs detection
methods and fixes the panic.
