filing-ui - pull "last modified" on the My Business Registry page

### Background
We want to show why last modified an entity, and when they did it, on the My Business Registry page.
There are a few implementations of this, some will make this page even slower. We want the fastest and most efficient.

We need to get this user data from auth api. Currently Auth API doesn't know how to redact user id stuff like our apps.

### To do
- [ ] Make a legal-api call for each business using business identifier to get "lastModified" and "submitter"

## 🛑 pausing grooming this ticket, we need to discuss:
* entities owning auth api
* the value of these fields, and the effort involved in implementing them.

Start with the My Business Registry page and the legal-api/auth API boundary described in the issue. Confirm ownership and the value of lastModified and submitter before implementation; grooming is paused and the issue does not define tests or clear completion criteria.

Written by the indexing model from the issue text.