Other eval features

[elray1]

Main idea of this discussion: what are all the things that we generally want to do as part of a forecast evaluation? Let's make sure we can do them all easily with hubverse tools.

Currently, features we've scoped out for this package are limited to computing scores, but there are lots of follow-on analyses that we generally want to do with scores:

• filling in missing forecasts or missing scores
• plotting scores, possibly alongside target data or the forecasts themselves, possibly facetted by some task id variable
• creating reports with sortable tables (related to dashboard, but could be simpler)

We could also think back to other one-off reports we've made and shared, and the kinds of figures and analyses we put in papers. It seems like we should provide functionality in hubverse packages, or point to functionality in places like scoringutils, for these things.