Indicate locked users in Admin Area users list

What does this MR do and why?

Related to #349848 (closed)

A user is locked after 10 failed login attempts. The lock expires after 10 minutes. An Admin can unlock a user from the Rails console or the Admin Area.

Previously there was no indication in the Admin Area user list view that a user is locked. This MR adds a Locked badge next to users that are locked.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Sign in as an Admin.
2. Navigate to /admin/users.
3. Click on a user and make note of their username.
4. In the Rails console (bin/rails console) run User.find_by_username(<Username from step 3>).update_column(:locked_at, DateTime.current).
5. Navigate back to the listing view. There should be a Locked badge next to the locked user

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.