Bug 35264: Add "protected" column to patron import

Bug 35264: Add "protected" column to patron import

This change adds the "protected" column to patron import.

Test plan:
0. Apply the patch and run "restart_all"
1. prove -v t/db_dependent/Koha/Patrons/Import.t
2. Go to http://localhost:8081/cgi-bin/koha/tools/import_borrowers.pl
3. Note "protected" is listed in the "fields you want to supply"
on the right side of the screen
4. Note "protected" appears in file downloaded by clicking
"Download a Starter CSV file with all the columns"
5. Note that "Protected" appears after clicking "Enter default values"
and after clicking "Preserve existing values"

6. For bonus marks, use the "Starter CSV file" to import a test patron
(remember surname, branchcode, and categorycode are the required fields)

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>