Bug 14322: Add shareable link button to item search

Bug 14322: Add shareable link button to item search

This patch adds a 'Copy shareable link' button to the item search results page.
When pasted into the browser the item search form will be prefilled.
The item search form submission still gets it's parameters from the form.

Test plan:
1. Apply patch
2. Try some item searches (try searches using the '+ New field' button too)
3. On the results page click the 'Copy shareable link' button
4. Paste the link into the browser and hit enter
5. Notice the item search form is filled out exactly as you did earlier
6. Click 'Search' and confirm the results are as you would expect
7. Click 'Edit search', modify the search and search again
8. Test the 'Copy shareable link' button again
9. Test pasting the example link below
10. With default ktd data the search will return one result for:
    	Intermediate Perl / Schwartz, Randal L.

http://localhost:8081/cgi-bin/koha/catalogue/itemsearch.pl?homebranch_op=%3D&homebranch=CPL&holdingbranch_op=%3D&holdingbranch=CPL&location_op=%3D&location=GEN&itype_op=%3D&itype=BK&ccode_op=%3D&ccode=REF&notforloan_op=!%3D&notforloan=1&itemlost_op=!%3D&itemlost=1&withdrawn_op=!%3D&withdrawn=1&damaged_op=!%3D&damaged=1&onloan=&f=publishercode&op=like&q=O'Reilly%2C&c=and&f=publicationyear&op=like&q=2006&c=and&f=title&op=not%20like&q=Javascript%20%3A&c=and&f=author&op=not%20like&q=Carlson%2C%20Lucas.&itemcallnumber_from=&itemcallnumber_to=&issues_op=%3E&issues=&datelastborrowed_op=%3E&datelastborrowed=&format=shareable

Sponsored-by: CLAMS
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Paul Derscheid <paul.derscheid@lmscloud.de>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>