Bug 16891: Move C4::Members::MoveMemberToDeleted to Koha::Patron->move_to_deleted

Bug 16891: Move C4::Members::MoveMemberToDeleted to Koha::Patron->move_to_deleted

This patch removes the C4::Members::MoveMemberToDeleted subroutine in
order to replace it with the Koha::Patron->move_to_deleted method.
Next after this change, we will move C4::Members::HandleDelBorrower and
C4::Members::DelMember to the same module to simplify the code in
members/deletemem.pl and misc/cronjobs/delete_patrons.pl

Test plan:
1/ Delete a patron from the staff interface and make sure (s)he has been moved to
the deletedborrowers table.
2/ Use the "Batch patron deletion" tool (tools/cleanborrowers.pl) to
remove patron. Make sure the "Permanently delete these patrons" and "Move
these patrons to the trash" options work as before
3/ Same as previously but using the cronjob
misc/cronjobs/delete_patrons.pl.

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Tested the delete_patrons.pl script and cleanborrowers.pl too.
Tests (are relevant and) pass and the qa scripts are happy too :-D

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>