WL#7033: Deprecate and remove mysql_setpermission

The mysql_setpermission Perl script provides an interactive means to manage user
permissions, but it hasn't kept up with recent developments, including new
permissions, user authentication plugins and proxy users, etc.  It should be
deprecated - users looking to manage user accounts interactively should use
MySQL Workbench.

See BUG#69016 Deprecate mysql_setpermission