General-use utils should have its own namespace

[JoelPasvolsky]

Generally useful decorator like cloud-client's @dwave.cloud.utils.retried or @dwave_networkx.utils.decorators.binary_quadratic_model_sampler that aren't limited in use to the particular repo that were written in should be under a generic dwave.utils or dwave.decorators namespace.

[arcondello]

I know that @randomir has been suggesting a dwave.common package or similar. Unfortunately, there is no nice way to populate a namespace from multiple packages (or at least none that I know of, though I haven't re-checked recently). dwavesystems/dwave-ocean-sdk#21 is an attempt to create one using entry points.

[randomir]

Yes, I still have dwave.common on my todo list. It would include:

• logging stuff
• profiling (like tictoc)
• testing utils, like various assertX
• misc commonly used utils like: @retried, @cached, @deprecated, etc.

Basically, utilities we use across multiple Ocean packages.