UserPublicProfile(): React.JSX.Element
Renders /@:username and its tabs, /@:username/:tab, and the follow
tab's view /@:username/follow/playlists, for anyone. useProfile loads
the user, by a former name or another case too, and the URL then takes the
current one; each tab loads its own lists, by the user's id, when shown.
On their own profile, users edit their avatar, description and email, and
create invites. The "manage" tab, another user's role and name, is for those
who hold user:manage. A tab or view the profile hasn't is NotFound.