Add admin note to user show page

Zendesk: https://gitlab.zendesk.com/agent/tickets/42164

A while back we added the ability for an admin to add a note about a user - https://gitlab.com/gitlab-org/gitlab-ee/issues/18. The current implementation shows a paper icon and hover reveals a tooltip to show the admin note. However, there is no indication of this admin note if an admin is viewing the user page.

Customer is suggesting we add the note as a pane on the right, above block and remove.

Paper icon and tooltip

Admin user show page

cc/ @gl-product