Expose QPU timing info in `timers`

[randomir]

Currently, SampleSet.info['timing'] as returned by the QPU sampler is discarded by our QPU hybrid samplers (like QPUSubproblemAutoEmbeddingSampler and others).

It would be useful to expose/store this info in hybrid sampler's timers structure, so it can be easily accessed and inspected.

An alternative is to subclass or reimplement the sampler, like here.