Function to load experiment state

[WarmCyan]

It's useful to have a notebook up while running experiments, and it would be convenient if there was a single function call that would just load the experiment state after it completes (so either by run name, or last by default)

e.g.

manager = cf.experiment.load_state()  # or `cf.experiment.load_state("some_experiment_6_...")`

In theory, by default this would be like an artifact exploration notebook #15 #artifact - it wouldn't actually run the experiment (could be an option to do so however)

This will likely need to rely on #58 and #60 completion