Bug 15814: Handle correctly MMTA edit button

Bug 15814: Handle correctly MMTA edit button

The MARC modification template action edit buton does not correctly
handle variable escaping.
Assigning a JS variable containing the JSON representation of the
hashref will make the processing much more easier.

Test plan:
Create a MARC Modification Template with several actions.
In the description you should use the following characters, to try to
break this patch: \ ' " \n \r
(not sure what we handled \n and \r)
Then edit the action, modify and save again.

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit 7a80483a1358a7bc3e516a8fbc92d34b6559dcac)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>