turbostat plugin: add new setting `RestoreAffinityPolicy`

turbostat plugin: add new setting `RestoreAffinityPolicy`

This new setting controls how the affinity is restored during
turbostat_read(). Two policies are implemented: AffinityRestore, and
AffinityAllCPUs. The default policy, AffinityRestore, behaves exactly
the same as before, which is to save affinity and to later restore it.
The second policy, RestoreAllCPUs, skips saving the affinity and
sets the affinity to all CPUs after each read. This second policy is
useful for systems where sched_getaffinity() fails and prevents data
collection.