BE: Max User count visualization - SaaS

Summary

When viewing Max User information, there's no timestamp or date info presented, so we don't have a sense of when a customer went over the limit if they owe a true-up. If we knew which month an instance went over their limit, we could look at users added during that month to give instances a good way to look back on why they went over.

Designs

#321933 (closed)

Frontend Issues

1. Technical breakdown#334689 (closed))
2. Create route
3. Feed data
4. Tweak graph
5. Feature flag rollout

Availability & Testing

We should edit the existing frontend specs (belonging to the component) to also account for the display of this column.