Bug 34966: Terminology - fix add item form (& to and)

This patch updates the add item form in the staff interface to
change the 'Add & duplicate' button to 'Add and duplicate'.

In our terminology guide, & should only be used when
it is part of a proper noun or a common abbreviation:
https://wiki.koha-community.org/wiki/Terminology

Test plan:
1. In the staff interface, search for and select a record.
2. Select New > New item.
3. Note that "Add & duplicate" is one of the action buttons at the
bottom of the add item form.
4. Apply the patch.
5. Refresh the page.
6. Note that the action button is now labelled 'Add and duplicate'.
7. Sign off! 8-)

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katariina Hanhisalo <katariina.hanhisalo@xamk.fi>
Signed-off-by: Reetta Pihlaja <reetta.pihlaja@siilinjarvi.fi>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit 34897afc59)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>

koha-tmpl/intranet-tmpl/prog/en/modules/cataloguing/additem.tt

@@ -268,7 +268,7 @@
     -->
     <span id="addsingle">
         <input type="submit" name="add_submit" value="Add item" onclick="return Check(this.form)" />
-        <input type="submit" name="add_duplicate_submit" value="Add &amp; duplicate" onclick="return Check(this.form)" />
+        <input type="submit" name="add_duplicate_submit" value="Add and duplicate" onclick="return Check(this.form)" />
     </span>
     <span id="addmultiple">
         <input type="button" name="add_multiple_copies" id="add_multiple_copies" value="Add multiple copies of this item" />