Bug 35383: Make subfields of repeated tags draggable

Bug 35383: Make subfields of repeated tags draggable

To reproduce:
1. Open any biblio and edit that record.
   (select "Edit record" from the "Edit" drop-down menu).
2. Repeat any tag that may be repeated and has more than one subfield
   (e.g. 050 or 082) (click "Repeat this tag")
3. Try dragging a subfield of the new repeated tag

Apply the patch and make sure dragging a subfield works well.

Signed-off-by: Phil Ringnalda <phil@chetcolibrary.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
(cherry picked from commit e99037989bcc239d2bffeac2c47e74ea4564d24e)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>