Add ability to export list of users in dolthub

**Is your feature request related to a problem? Please describe.**
Our company's security team performs an audit of users quarterly and we need an easy/automated way to provide this list

**Describe the solution you'd like**
A button in dolthub to export the list of users, their roles, and their email as a .csv and send it to a specified email

**Describe alternatives you've considered**
Right now I keep track in a google sheet that I have to manually update

The issue does not name files, tests, or an entry point. Begin by locating DoltHub's user-management area and clarifying the CSV fields, recipient handling, and delivery behavior; done means users, roles, and email can be exported and sent to a specified address.

Written by the indexing model from the issue text.