Bug 35425: Optimize UX when dragging a tag or subfield

Bug 35425: Optimize UX when dragging a tag or subfield

To reproduce:
1. Open any biblio and edit that record.
   (select "Edit record" from the "Edit" drop-down menu).
2. Check that selecting the text in any draggable block input/textarea
   fields with a mouse is not possible - it starts dragging instantly.
3. Apply the patch
4. Make sure that draging is activated only when you click
   on the "::" icon in front of the dragged item. And text selection
   works correctly.

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>