203 update scoringutils 2.0.0

[kaitejohnson]

This PR closes #203. It uses v2.0.0 of scoringutils to compute the full set of scores based on the samples and quantiles of the forecasted hospital admissions in the evaluation pipeline.

Note this is a WIP. Currently we have just edited the inputs to scoringutils::score() which expects new names for the predicted and observed values and requires converting from a data.table to a forecast object. For compatibility with the rest of the downstream functions (mostly plotting) I converted names back to what we had previously named the columns (true_value and prediction). This might be incompatible with summarise_scores().

To do

• [ ] test eval_postprocess() locally on a ww_fit_obj and ensure the scores are equivalent or nearly to the previous implementation
• [ ] run on full _targets_eval_postprocessing.R or targets_subset_benchmarking.R to ensure compatibility with downstream scoringutils functions

[kaitejohnson]

Going to close as not planned for now