Change user types in the UI

This suggestion comes from community.
Currently the only way to change the role of a user is to use the API.

**Proposal:**
Allow owners to change the role of other users in the UI.
Currently you can create a user with an all access token with the API or the CLI. However this user isn't considered an owner even though owners have the same permissions.
If you want to change the role of an official owner or user with owner permissions you have to:
1. delete the user
2. create new one with the appropriate permissions

**Current behavior:**
You can only create a user.

**Desired behavior:**
Be able to change the user. Maybe have a settings button similar to the buckets page where you can change the retention policy.

**Alternatives considered:**
An API experience that supports the ability to change a user's role without having to delete it first.
A CLI experience that allows you to delete a user.

Review the current user-creation UI and the buckets-page settings pattern mentioned in the proposal. Trace how user roles and owner permissions are represented in the UI, then define the interaction for changing an existing user's role and verify that the completed flow supports the desired role changes without deleting the user.

Written by the indexing model from the issue text.