Bug 34519: Add a template plugin for fetch searchable patron attributes

Bug 34519: Add a template plugin for fetch searchable patron attributes

This patch moves code form scripts to a template plguin and unifies the calls

To test:
1 - Add a searchable patron attribute type
2 - Add values to several patrons and test patron searching from
    Patrons home
    Patrons search results
    Holds request screen
    Article request screen
    Patron search sidebar
3 - Apply patch
4 - Confirm results are the same

Signed-off-by: Janusz Kaczmarek <januszop@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>