Bug 23385: (follow-up) Update link

Bug 23385: (follow-up) Update link

This follow-up adds a dummy href attribute to the link for showing and
hiding the default values form so that it behaves more like a link.

I removed "click to" from the link text and added Font Awesome icons
common to "show/hide" links.

Signed-off-by: George Williams <george@nekls.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit 0a66d33d8c5d778e3a0961cb5953e2432d9ccb65)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>