feat(nimbus): create cards for other experiment metrics

[moibra05]

Because

• Results page was only showing kpi metrics
• Cards were not collapsible

This commit

• Displays all the metrics associated with an experiment (kpi, outcomes, defaults)
• Groups metrics by outcomes (for now) and alphabetically
• Adds a "Notable Changes" section where only metrics that have at least once branch with a stat significance change are shown

Fixes #13721

[moibra05]

[freshstrangemusic]

we might want to consider moving some of the metrics calculation gunk (e.g., every function we're adding that isnt going to be called outside of /results/) off of the model itself and into the results app, but that can be done in a follow-up.