Represents a single duration you have tracked and named, usually to
time code segments. Light wrapper around [‘std::time::Instant’].
Spawning with Self::new() immediately starts tracking a duration, then you Self::finish()
it when done. You would then normally add it to a OneList<T>
A threadsafe list to be shared between contexts or threads. Inexpensive clones,
all clones point to the same list. Combine with OneDuration for aggregating
code timings