LP#1792482 My OPAC settings preferred name field

LP#1792482 My OPAC settings preferred name field

Adds a new row to the patron account preferences page for Preferred
Name.  The field only displays when a preferred first, middle, or last
value is present and follows the same display logic as preferred names
in the staff client, where first and last fall-through to the primary
name.

Signed-off-by: Bill Erickson <berickxx@gmail.com>