Time samples should be saved with ROQ weights

Currently, there's an option to save the ROQ weights to disk so they can be loaded later. This currently doesn't store the time samples.

This means that the time samples are recomputed when the weights are loaded, but if the IFO network has changed (e.g. for coherence tests) these will not match leading to bias in the time posterior and other parameters as a consequence.

We should save the time_samples in the same dictionary as the weights.