Bug 15437: MARC21: Show $i for 780/785

Bug 15437: MARC21: Show $i for 780/785

Test Plan
1: Inside Administration go to MARC bibliographic framework and on the
default framework under Actions click on MARC structure
2: Search for 780 under search tag and under actions click subfields
3: Find i and click on edit.
4: Under Advanced Constraints select editor and save the changes.
5: Repeat for 785.
6: Find a Bibliograpical record and under Edit select edit record.
7: Under the 7 put values into 780 and 785. For this to work it is
dependant on the patch 17929 so that you can type into the indicators
8: When you save the changes you won't be able to see 780 or 785 on the
Bibliographical details
8: Apply the patch
9: Refresh and 780 and 785 should be there at the bottom under the
content

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>