LP#1792482 Only require first/last in pref name display

LP#1792482 Only require first/last in pref name display

When displaying a patrons preferred name, always show a value for first
and last name, starting with the preferred name and defaulting to the
primary name, but only show values for prefix, middle name, and suffix
when a preferred variant is applied.

This avoids scenarios where patrons use their middle name as their first
name, with no preferred middle name applied, resulting duplicate
first/middle names displaying.

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